256 lines
14 KiB
JSON
256 lines
14 KiB
JSON
{
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"dataType": "CVE_RECORD",
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"dataVersion": "5.2",
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"cveMetadata": {
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"cveId": "CVE-2026-89537",
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"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"state": "PUBLISHED",
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"assignerShortName": "Linux",
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"dateReserved": "2026-09-11T19:38:34.721Z",
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"datePublished": "2026-09-11T19:44:15.216Z",
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"dateUpdated": "2026-10-30T12:32:04.586Z"
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},
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"containers": {
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"cna": {
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"providerMetadata": {
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"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"shortName": "Linux",
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"dateUpdated": "2026-10-30T12:32:04.586Z"
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},
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"descriptions": [
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{
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"lang": "en",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: Reject short RFC 4121 MIC tokens in gss_krb5_verify_mic_v2\n\ngss_krb5_verify_mic_v2() reads the token ID at ptr[0..1], the flags\nbyte at ptr[2], and padding at ptr[3..7], then passes\nptr + GSS_KRB5_TOK_HDR_LEN and cksum_len to gss_krb5_mic_build_sg().\nNone of these accesses check read_token->len first.\n\nThe minimum safe token size is GSS_KRB5_TOK_HDR_LEN (16) plus\nctx->krb5e->cksum_len (12-24, depending on the enctype). All callers\naccept shorter tokens from the wire:\n\n - gss_unwrap_resp_integ() enforces only an upper bound\n (offset + len <= rcv_buf->len) before allocating\n mic.data = kmalloc(len) and passing it to gss_verify_mic().\n A malicious NFS server can therefore supply a short checksum\n opaque, producing a small slab allocation that the Kerberos MIC\n verifier reads past.\n\n - gss_validate() enforces only len <= RPC_MAX_AUTH_SIZE (400)\n before passing the wire-supplied length to\n gss_validate_seqno_mic(), which constructs a mic xdr_netobj\n and calls gss_verify_mic().\n\n - svcauth_gss_verify_header() enforces only\n checksum.len >= XDR_UNIT (4 bytes) before dispatching to\n gss_verify_mic().\n\n - svcauth_gss_unwrap_integ() checks only that the checksum fits\n in gsd->gsd_scratch.\n\nAdd a length guard at the top of gss_krb5_verify_mic_v2(), before any\nptr[] access or scatterlist construction. Well-formed MIC tokens from\ngss_krb5_get_mic_v2() already have exactly GSS_KRB5_TOK_HDR_LEN +\ncksum_len bytes, so valid traffic is unaffected."
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}
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],
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"metrics": [
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{
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"cvssV3_1": {
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"version": "3.1",
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"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
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"baseScore": 9.1,
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"baseSeverity": "CRITICAL"
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},
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"scenarios": [
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{
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"lang": "en",
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"value": "AV:N - gss_krb5_verify_mic_v2() is reached from nfsd RPCSEC_GSS on TCP/2049 (svcauth_gss_accept → svcauth_gss_verify_header/unwrap_integ) and from the NFS client processing a remote server's RPCSEC_GSS verifier or krb5i checksum, so a remote peer triggers it with crafted SUNRPC traffic.\nAC:L - A single RPCSEC_GSS Call or Reply with a MIC/checksum shorter than GSS_KRB5_TOK_HDR_LEN plus cksum_len (callers accept as little as 4 bytes) deterministically over-reads; no race or attacker-uncontrollable layout is required. Kerberized NFS is a standard enterprise deployment.\nPR:N - svcauth_gss_verify_header() is the MIC check itself and runs before credentials are verified; the only gate is an rsc-cache lookup on a cleartext, monotonically increasing 64-bit GSS handle that an unauthenticated client can sniff or enumerate. A malicious NFS server needs no privileges on the client.\nUI:N - On nfsd the over-read is triggered solely by an inbound RPCSEC_GSS message; on the client it fires from the RPC receive path once an NFS/RPCSEC_GSS mount exists. No separate victim action is required at attack time.\nS:U - The slab over-read and any resulting oops stay inside the host kernel SUNRPC/GSS code. This is ordinary same-host kernel impact, not a VM escape, IOMMU bypass, or other changed-scope boundary.\nC:H - gss_unwrap_resp_integ() kmallocs only the attacker-chosen checksum length, then gss_krb5_verify_mic_v2() reads GSS_KRB5_TOK_HDR_LEN+cksum_len (28-40) bytes via gss_krb5_mic_build_sg()/sg_pcopy_to_buffer, an out-of-bounds read of adjacent slab well beyond a few bytes.\nI:N - The defect is a read-only over-read consumed as a MIC comparison; rfc3961_verify_mic copies those bytes into a local buffer and memcmp()s them. There is no out-of-bounds write, use-after-free, or control-flow hijack primitive.\nA:H - Reading 28-40 bytes past a small kmalloc object or past an RPC receive buffer near a page boundary can oops or panic on KASAN, redzone, or unmapped next-page kernels, and the attacker can repeat the crafted RPC to deny NFS service."
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}
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]
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}
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],
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"affected": [
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "unaffected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"net/sunrpc/auth_gss/gss_krb5_unseal.c"
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],
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"versions": [
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{
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"version": "de9c17eb4a912c9028f7b470eb80815144883b26",
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"lessThan": "86c3d527303ec79805098bda3dfc4fa994757f59",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "de9c17eb4a912c9028f7b470eb80815144883b26",
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"lessThan": "b2e9e10f5a536befcdce64d3e6946dff42fb823e",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "de9c17eb4a912c9028f7b470eb80815144883b26",
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"lessThan": "997577c52487181226775db3755079a3ba1d52b9",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "de9c17eb4a912c9028f7b470eb80815144883b26",
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"lessThan": "996dd15f60121bdd7896b4554458f8806d608063",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "de9c17eb4a912c9028f7b470eb80815144883b26",
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"lessThan": "7a946b2e7207f968902f2147ab9b30726f82f7ab",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "de9c17eb4a912c9028f7b470eb80815144883b26",
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"lessThan": "b94f6719dcd9f7a609bc5f459f85795900e77d25",
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"status": "affected",
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"versionType": "git"
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}
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]
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},
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "affected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"net/sunrpc/auth_gss/gss_krb5_unseal.c"
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],
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"versions": [
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{
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"version": "2.6.35",
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"status": "affected"
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},
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{
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"version": "0",
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"lessThan": "2.6.35",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.1.191",
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"lessThanOrEqual": "6.1.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.6.160",
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"lessThanOrEqual": "6.6.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.12.114",
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"lessThanOrEqual": "6.12.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.18.57",
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"lessThanOrEqual": "6.18.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.2.4",
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"lessThanOrEqual": "7.2.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.3",
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"lessThanOrEqual": "*",
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"status": "unaffected",
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"versionType": "original_commit_for_fix"
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}
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]
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}
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],
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"cpeApplicability": [
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{
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"nodes": [
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{
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"operator": "OR",
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"negate": false,
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"cpeMatch": [
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "2.6.35",
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"versionEndExcluding": "6.1.191"
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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]
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}
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],
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/86c3d527303ec79805098bda3dfc4fa994757f59"
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},
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{
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"url": "https://git.kernel.org/stable/c/b2e9e10f5a536befcdce64d3e6946dff42fb823e"
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},
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{
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"url": "https://git.kernel.org/stable/c/997577c52487181226775db3755079a3ba1d52b9"
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},
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{
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"url": "https://git.kernel.org/stable/c/996dd15f60121bdd7896b4554458f8806d608063"
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},
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{
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"url": "https://git.kernel.org/stable/c/7a946b2e7207f968902f2147ab9b30726f82f7ab"
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},
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{
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"url": "https://git.kernel.org/stable/c/b94f6719dcd9f7a609bc5f459f85795900e77d25"
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}
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],
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"title": "SUNRPC: Reject short RFC 4121 MIC tokens in gss_krb5_verify_mic_v2",
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"x_generator": {
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"engine": "bippy-1.2.0"
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}
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},
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"adp": [
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{
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"metrics": [
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{
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"other": {
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"type": "ssvc",
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"content": {
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"id": "CVE-2026-89537",
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"role": "CISA Coordinator",
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"options": [
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{
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"Exploitation": "none"
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},
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{
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"Automatable": "yes"
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},
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{
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"Technical Impact": "partial"
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}
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],
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"version": "2.0.3",
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"timestamp": "2026-10-16T19:23:15.980324Z"
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}
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}
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}
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],
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"title": "CISA ADP Vulnrichment",
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"providerMetadata": {
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"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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"shortName": "CISA-ADP",
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"dateUpdated": "2026-10-16T19:26:41.729Z"
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}
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}
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]
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}
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} |