keys: Avoid the owner account dereference in named keyring lookup
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- No fix listed
- Who is exposed
- Not reported
Do first: Workaround: 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.
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- Published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 25/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Unclear
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
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.
Read the original 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
Workaround: 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.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- Linux Linux
Version range not reported
- Linux Linux
2.6.30
Evidence 8
- Link
- Link
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Corrections
None so far.
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Questions about CVE-2026-99226
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: git.kernel.org
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: git.kernel.org
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: git.kernel.org
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: cve.now feed data
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: git.kernel.org