200 lines
11 KiB
JSON
200 lines
11 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-2025-39840",
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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": "2025-04-16T07:20:57.141Z",
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"datePublished": "2025-09-19T15:26:15.596Z",
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"dateUpdated": "2026-08-05T12:05:33.644Z"
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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": "2026-08-05T12:05:33.644Z"
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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\naudit: fix out-of-bounds read in audit_compare_dname_path()\n\nWhen a watch on dir=/ is combined with an fsnotify event for a\nsingle-character name directly under / (e.g., creating /a), an\nout-of-bounds read can occur in audit_compare_dname_path().\n\nThe helper parent_len() returns 1 for \"/\". In audit_compare_dname_path(),\nwhen parentlen equals the full path length (1), the code sets p = path + 1\nand pathlen = 1 - 1 = 0. The subsequent loop then dereferences\np[pathlen - 1] (i.e., p[-1]), causing an out-of-bounds read.\n\nFix this by adding a pathlen > 0 check to the while loop condition\nto prevent the out-of-bounds access.\n\n[PM: subject tweak, sign-off email fixes]"
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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:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
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"baseScore": 7.1,
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"baseSeverity": "HIGH"
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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:L - The vulnerable code is reached only through the syscall audit context (`__audit_getname`/`__audit_inode_child`) or an fsnotify event on a locally-installed audit watch, both of which require issuing local syscalls such as symlink()/mkdir()/rename(). No network-facing kernel service (nfsd/ksmbd) builds audit name entries via getname(), so there is no remote path to the defect.\nAC:L - The attacker fully controls both inputs — an all-slash pathname argument and the basename of the created child — so the backwards walk past the start of the buffer is triggered deterministically on every attempt, with no race to win and no timing dependency. Padding the slash string to ≥EMBEDDED_NAME_MAX deterministically forces the string into a page-aligned names_cachep object, so even the page-boundary read is attacker-arranged.\nPR:L - Any unprivileged local user can call symlink(\"///…\", \"/tmp/x\") in a world-writable directory; no capability, namespace trick, or audit privilege is needed, and the AUDIT_TYPE_UNKNOWN found_child branch bypasses the ino/dev ownership check entirely. The only precondition is a system-wide audit ruleset installed by the administrator, which is an environmental condition rather than an attacker privilege.\nUI:N - The attacking process performs the whole sequence itself in a single syscall; no victim has to mount a filesystem, open a file, or take any other action.\nS:U - The out-of-bounds read occurs in kernel heap memory and both the flaw and its consequences stay within the kernel's own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - This is an out-of-bounds read that is not bounded to a few bytes — the loop keeps decrementing and dereferencing backwards for as long as the preceding kernel memory contains 0x2f bytes, so an attacker who sprays '/' bytes into the heap can extend the walk across adjacent slab objects and pages, touching arbitrary kernel memory beyond the allocation.\nI:N - The defect performs only reads; `pathlen` becomes negative so the comparison always returns \"no match\" and `memcmp()` is unreachable, leaving no memory write, no control-flow influence, and no change to the audit records that would be emitted.\nA:H - With a slash string long enough to occupy a page-aligned 4096-byte names_cachep object, the walk immediately dereferences the byte before a page boundary and can continue across pages, producing a kernel oops on an unmapped/guard page under KFENCE, DEBUG_PAGEALLOC, or a direct-map hole, and a fatal KASAN report on hardened kernels; it is repeatable at will by an unprivileged user."
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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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"kernel/auditfilter.c"
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],
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"versions": [
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{
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"version": "e92eebb0d6116f942ab25dfb1a41905aa59472a8",
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"lessThan": "9735a9dcc307427e7d6336c54171682f1bac9789",
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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": "e92eebb0d6116f942ab25dfb1a41905aa59472a8",
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"lessThan": "4540f1d23e7f387880ce46d11b5cd3f27248bf8d",
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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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"kernel/auditfilter.c"
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],
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"versions": [
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{
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"version": "6.14",
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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": "6.14",
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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": "6.16.6",
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"lessThanOrEqual": "6.16.*",
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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": "6.17",
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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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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.14",
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"versionEndExcluding": "6.16.6"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.14",
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"versionEndExcluding": "6.17"
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}
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]
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}
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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/9735a9dcc307427e7d6336c54171682f1bac9789"
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},
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{
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"url": "https://git.kernel.org/stable/c/4540f1d23e7f387880ce46d11b5cd3f27248bf8d"
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}
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],
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"title": "audit: fix out-of-bounds read in audit_compare_dname_path()",
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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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"cvssV3_1": {
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"scope": "UNCHANGED",
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"version": "3.1",
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"baseScore": 7.1,
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"attackVector": "LOCAL",
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"baseSeverity": "HIGH",
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"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
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"integrityImpact": "NONE",
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"userInteraction": "NONE",
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"attackComplexity": "LOW",
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"availabilityImpact": "HIGH",
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"privilegesRequired": "LOW",
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"confidentialityImpact": "HIGH"
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}
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},
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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-2025-39840",
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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": "no"
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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": "2026-01-14T19:20:33.496174Z"
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}
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}
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}
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],
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"problemTypes": [
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{
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"descriptions": [
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{
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"lang": "en",
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"type": "CWE",
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"cweId": "CWE-125",
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"description": "CWE-125 Out-of-bounds Read"
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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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"shortName": "CISA-ADP",
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"dateUpdated": "2026-01-14T19:23:12.172Z"
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} |