{"id":"CVE-2026-53162","state":"PUBLISHED","title":"memcg: use round-robin victim selection in refill_stock","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmemcg: use round-robin victim selection in refill_stock\n\nHarry Yoo reported that get_random_u32_below() is not safe to call in the\nnmi context and memcg charge draining can happen in nmi context.\n\nMore specifically get_random_u32_below() is neither reentrant- nor\nNMI-safe: it acquires a per-cpu local_lock via local_lock_irqsave() on the\nbatched_entropy_u32 state.  An NMI that lands on a CPU mid-update of the\nChaCha batch state and recurses into the random subsystem would corrupt\nthat state.  The memcg_stock local_trylock prevents re-entry on the percpu\nstock itself, but cannot protect an unrelated subsystem's per-cpu lock.\n\nReplace the random pick with a per-cpu round-robin counter stored in\nmemcg_stock_pcp and serialized by the same local_trylock that already\nguards cached[] and nr_pages[].  No atomics, no random calls, no extra\nlocks needed.","publishedAt":"2026-06-25T08:38:43.453Z","updatedAt":"2026-08-05T12:33:37.176Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"f735eebe55f8f61758fe014bd0b02ab50b059e4d","status":"affected","lessThan":"89bd8215e25aa6999cc51696da418e0d422bc5e0","versionType":"git"},{"version":"f735eebe55f8f61758fe014bd0b02ab50b059e4d","status":"affected","lessThan":"00731bd7e18f182a32ca54d6b176eaa470b51ed7","versionType":"git"},{"version":"f735eebe55f8f61758fe014bd0b02ab50b059e4d","status":"affected","lessThan":"c0cafe24d3f6534294c4b2bc2d47734ff7cbd313","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/memcontrol.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.16","versionType":"semver"},{"version":"6.18.36","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.13","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/memcontrol.c"]}],"references":["https://git.kernel.org/stable/c/89bd8215e25aa6999cc51696da418e0d422bc5e0","https://git.kernel.org/stable/c/00731bd7e18f182a32ca54d6b176eaa470b51ed7","https://git.kernel.org/stable/c/c0cafe24d3f6534294c4b2bc2d47734ff7cbd313"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:16.098Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/53xxx/CVE-2026-53162.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-53162","state":"PUBLISHED","datePublished":"2026-06-25T08:38:43.453Z","dateUpdated":"2026-08-05T12:33:37.176Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-06-09T07:44:35.388Z"},"containers":{"cna":{"title":"memcg: use round-robin victim selection in refill_stock","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nmemcg: use round-robin victim selection in refill_stock\n\nHarry Yoo reported that get_random_u32_below() is not safe to call in the\nnmi context and memcg charge draining can happen in nmi context.\n\nMore specifically get_random_u32_below() is neither reentrant- nor\nNMI-safe: it acquires a per-cpu local_lock via local_lock_irqsave() on the\nbatched_entropy_u32 state.  An NMI that lands on a CPU mid-update of the\nChaCha batch state and recurses into the random subsystem would corrupt\nthat state.  The memcg_stock local_trylock prevents re-entry on the percpu\nstock itself, but cannot protect an unrelated subsystem's per-cpu lock.\n\nReplace the random pick with a per-cpu round-robin counter stored in\nmemcg_stock_pcp and serialized by the same local_trylock that already\nguards cached[] and nr_pages[].  No atomics, no random calls, no extra\nlocks needed."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"f735eebe55f8f61758fe014bd0b02ab50b059e4d","status":"affected","lessThan":"89bd8215e25aa6999cc51696da418e0d422bc5e0","versionType":"git"},{"version":"f735eebe55f8f61758fe014bd0b02ab50b059e4d","status":"affected","lessThan":"00731bd7e18f182a32ca54d6b176eaa470b51ed7","versionType":"git"},{"version":"f735eebe55f8f61758fe014bd0b02ab50b059e4d","status":"affected","lessThan":"c0cafe24d3f6534294c4b2bc2d47734ff7cbd313","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/memcontrol.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.16","versionType":"semver"},{"version":"6.18.36","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.13","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/memcontrol.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/89bd8215e25aa6999cc51696da418e0d422bc5e0"},{"url":"https://git.kernel.org/stable/c/00731bd7e18f182a32ca54d6b176eaa470b51ed7"},{"url":"https://git.kernel.org/stable/c/c0cafe24d3f6534294c4b2bc2d47734ff7cbd313"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The vulnerable `refill_stock()` path is reached through local kernel activity such as memcg-accounted allocation/free paths and NMI-capable perf/BPF-style execution, not by unauthenticated network packets alone.\nAC:L - An attacker can repeatedly drive memcg stock eviction and high-rate NMI/RNG activity; the race is timing-sensitive but both sides are influenceable from local execution.\nPR:L - Reachability requires a local user context able to create or use memcg-accounted workloads and NMI-capable facilities such as perf/BPF or delegated equivalents, so low privileges are sufficient in a plausible deployment.\nUI:N - No separate victim action is required once the attacker can run the local workload and trigger the accounting/NMI activity.\nS:U - The corrupted state is inside the same kernel security authority; this is not a VM, IOMMU, or sandbox boundary escape by itself.\nC:H - The bug corrupts per-CPU random subsystem batch state used for security-sensitive randomness, so confidentiality impact is high under the required higher-severity assumption.\nI:H - Corruption of kernel RNG state can undermine integrity of random-dependent kernel protections and identifiers, and the vulnerable interleaving includes state writes outside the intended entropy slot.\nA:H - Kernel per-CPU state corruption in NMI context can lead to unpredictable kernel malfunction or hard failure, so availability impact is high."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:33:37.176Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.16","versionEndExcluding":"6.18.36"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.16","versionEndExcluding":"7.0.13"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.16","versionEndExcluding":"7.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}