Raw vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2026-23161 is a high-severity Race Condition (CWE-362) vulnerability in Linux Linux Kernel. Its CVSS base score is 7.3 (High).
Operationally, ranked at the 0.9th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SC-39 (Process Isolation) and SC-4 (Information in Shared System Resources) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-23161 is a race condition vulnerability in the Linux kernel's memory management subsystems, specifically affecting the mm/shmem and swap components. The issue arises in the shmem swap freeing helper, which fails to correctly handle the order of swap entries. It retrieves the entry order using xa_get_order without lock protection, potentially obtaining an outdated value if the entry is split or modified before the subsequent xa_cmpxchg_irq operation. This can allow the order to exceed expected bounds, leading to truncation that erases data beyond the file's end boundary.
A local attacker with low privileges can exploit this vulnerability with low attack complexity and no user interaction required. Successful exploitation may result in limited confidentiality impact, high integrity impact through data corruption or improper truncation, and high availability impact, such as kernel panics or hangs during operations like swapoff. The CVSS v3.1 base score of 7.3 (AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H) reflects these characteristics, tied to CWE-362 (concurrent execution using shared resource with improper synchronization).
Mitigation is provided through kernel patches available in stable releases, as detailed in the referenced commits: https://git.kernel.org/stable/c/8a1968bd997f45a9b11aefeabdd1232e1b6c7184, https://git.kernel.org/stable/c/a99f9a4669a04662c8f9efe0e62cafc598153139, and https://git.kernel.org/stable/c/b23bee8cdb7aabce5701a7f57414db5a354ae8ed. These patches open-code the Xarray cmpxchg operation to ensure order retrieval and value checking occur within the same critical section, while also skipping large swap entries that cross the end boundary to prevent over-truncation. The fix resolved observed swapoff hangs and kernel panics during stress testing of ZSWAP with shmem.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-5877
Vulnerability Data
In the Linux kernel, the following vulnerability has been resolved: mm/shmem, swap: fix race of truncate and swap entry split The helper for shmem swap freeing is not handling the order of swap entries correctly. It uses xa_cmpxchg_irq to erase…
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the swap entry, but it gets the entry order before that using xa_get_order without lock protection, and it may get an outdated order value if the entry is split or changed in other ways after the xa_get_order and before the xa_cmpxchg_irq. And besides, the order could grow and be larger than expected, and cause truncation to erase data beyond the end border. For example, if the target entry and following entries are swapped in or freed, then a large folio was added in place and swapped out, using the same entry, the xa_cmpxchg_irq will still succeed, it's very unlikely to happen though. To fix that, open code the Xarray cmpxchg and put the order retrieval and value checking in the same critical section. Also, ensure the order won't exceed the end border, skip it if the entry goes across the border. Skipping large swap entries crosses the end border is safe here. Shmem truncate iterates the range twice, in the first iteration, find_lock_entries already filtered such entries, and shmem will swapin the entries that cross the end border and partially truncate the folio (split the folio or at least zero part of it). So in the second loop here, if we see a swap entry that crosses the end order, it must at least have its content erased already. I observed random swapoff hangs and kernel panics when stress testing ZSWAP with shmem. After applying this patch, all problems are gone.
- CWE(s)
Related Threats
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Maintaining separate execution domains for each process structurally eliminates unintended concurrent access to the same shared resources.
Preventing unintended information transfer through shared system resources directly addresses the improper concurrent modification that defines a race condition.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing can detect race conditions, but does not prevent them at design or coding time.
Secure coding standards explicitly forbid unsafe concurrent access patterns and mandate atomic operations or locks.
Hardening callouts derived
DISA STIG baselines are authored against specific weaknesses. Where this CVE cites a broad weakness class, the mapping is not asserted at that abstraction (owner ruling, 2026-09-25: grade only at Base and below), so no rule is shown here rather than a rule shown against the wrong grain.
- No fine-grained STIG row for CWE-362, a class-level weakness, and none of its children carries one either.