130 lines
7.0 KiB
JSON
130 lines
7.0 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-2026-79979",
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"assignerOrgId": "e2e69745-5e70-4e92-8431-deb5529a81ad",
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"state": "PUBLISHED",
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"assignerShortName": "zephyr",
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"dateReserved": "2026-08-25T16:06:32.777Z",
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"datePublished": "2026-10-23T19:56:16.111Z",
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"dateUpdated": "2026-11-02T13:54:45.589Z"
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},
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"containers": {
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"cna": {
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"providerMetadata": {
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"orgId": "e2e69745-5e70-4e92-8431-deb5529a81ad",
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"shortName": "zephyr",
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"dateUpdated": "2026-10-23T19:56:16.111Z"
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},
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"title": "Stale TLB entries after demand-paging page-out let arm64 user threads access reused physical frames",
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"descriptions": [
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{
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"lang": "en",
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"value": "The arm64 MMU backend invalidates a single virtual address from the TLB with invalidate_tlb_page() in arch/arm64/core/mmu.c, which issued TLBI VAE1{IS} with an operand of virt >> 12. That operand encodes the ASID in bits [63:48], so the invalidation only ever matched ASID 0 (the kernel page tables) and global entries. Memory domains, however, are allocated ASIDs starting at 1 in arch_mem_domain_init(), and every domain-private leaf created by private_map() is mapped with MT_NG, i.e. non-global. A domain's cached translation therefore survived the invalidation.\n\nAll callers of invalidate_tlb_page() are demand-paging paths. When the eviction algorithm reclaims a frame, page_frame_prepare_locked() in kernel/mmu.c calls arch_mem_page_out(), which marks the kernel leaf invalid, propagates the invalid descriptor into every domain via sync_domains(), and then flushes only ASID 0. do_page_fault() immediately reuses the very same page frame for the incoming mapping through arch_mem_page_in(). A user thread that had already touched the evicted page — a k_mem_partition added with arch_mem_domain_partition_add(), or its own stack mapped by map_thread_stack() — retains a valid EL0 read/write translation to that physical frame under its own ASID.\n\nUnprivileged code running in a user thread can drive memory pressure to force eviction and then keep accessing the stale address, obtaining read and write access to whatever the kernel subsequently placed in that frame: supervisor data, another memory domain's partition, or another thread's stack. This defeats the isolation that CONFIG_USERSPACE is meant to enforce, allowing information disclosure and memory corruption up to full compromise of the system.\n\nThe fix switches the implementation to TLBI VAAE1{IS}, which matches every ASID and both global and non-global entries, so no domain-tagged translation survives a page out, dirty-bit update or access-flag clear. Exploitation requires an arm64 build with both CONFIG_USERSPACE and CONFIG_DEMAND_PAGING enabled, an active backing store, and at least one demand-paged page that is also privately mapped into a user memory domain. The same commit additionally stops globalize_table() from stripping EL0 permission and non-global attributes off domain-private leaves during paging synchronization, which previously caused user threads to lose access to their own partitions and stacks."
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}
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],
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"affected": [
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{
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"vendor": "zephyrproject",
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"product": "zephyr",
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"collectionURL": "https://github.com/zephyrproject-rtos/zephyr",
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"packageName": "zephyr",
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"defaultStatus": "unaffected",
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"programFiles": [
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"arch/arm64/core/mmu.c"
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],
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"programRoutines": [
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{
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"name": "arch_mem_page_out"
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},
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{
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"name": "invalidate_tlb_page"
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}
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],
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"versions": [
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{
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"version": "4.3.0",
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"status": "affected",
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"lessThan": "4.5.0",
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"versionType": "semver"
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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://github.com/zephyrproject-rtos/zephyr/commit/d732e9f808f16911d06769b3f756246f3528669f",
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"name": "Fix commit",
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"tags": [
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"patch"
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]
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},
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{
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"url": "https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-6pqm-hfxf-48qv",
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"name": "GHSA-6pqm-hfxf-48qv"
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}
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],
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"metrics": [
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{
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"format": "CVSS",
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"cvssV3_1": {
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"version": "3.1",
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"vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H",
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"baseScore": 7.8,
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"baseSeverity": "HIGH"
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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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"description": "use-after-free",
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"cweId": "CWE-416",
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"type": "CWE"
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}
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]
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}
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],
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"x_generator": {
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"engine": "cvelib 1.8.0"
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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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"timestamp": "2026-11-02T13:54:32.260457Z",
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"id": "CVE-2026-79979",
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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": "total"
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}
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],
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"role": "CISA Coordinator",
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"version": "2.0.3"
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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": "2026-11-02T13:54:45.589Z"
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}
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}
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]
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}
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} |