Linux: Improper Synchronization
CVE-2026-68149 is a high-severity improper synchronization vulnerability in Linux, with a CVSS 3.1 base score of 8.4 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions b98fad81f1202b0eb26aacf3ff4cc7a21ed3b5bf, 834ddf899484a2f23129080e8773bc04f4691d07, a019b074903b3ad0a9726087efd0e8291452023b as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.14% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to b98fad81f1202b0eb26aacf3ff4cc7a21ed3b5bf or 834ddf899484a2f23129080e8773bc04f4691d07 or a019b074903b3ad0a9726087efd0e8291452023b or ca03a7984a34f48085fd013e0d2cf4e6420b4acf, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | facd61053cff100973921d4d45d47cf53c747ec6 up to, but not including, b98fad81f1202b0eb26aacf3ff4cc7a21ed3b5bf; facd61053cff100973921d4d45d47cf53c747ec6 up to, but not including, 834ddf899484a2f23129080e8773bc04f4691d07; facd61053cff100973921d4d45d47cf53c747ec6 up to, but not including, a019b074903b3ad0a9726087efd0e8291452023b; facd61053cff100973921d4d45d47cf53c747ec6 up to, but not including, ca03a7984a34f48085fd013e0d2cf4e6420b4acf; facd61053cff100973921d4d45d47cf53c747ec6 up to, but not including, 4b9a5458d02e214ef2b384124ca626e3e381d778; 6.2 | b98fad81f1202b0eb26aacf3ff4cc7a21ed3b5bf, 834ddf899484a2f23129080e8773bc04f4691d07, a019b074903b3ad0a9726087efd0e8291452023b, ca03a7984a34f48085fd013e0d2cf4e6420b4acf, 4b9a5458d02e214ef2b384124ca626e3e381d778 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N. Scored by CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: fs: preserve ACL_DONT_CACHE state in forget_cached_acl() The ACL_DONT_CACHE state is meant to be a constant state for the inode for filesystems that want to opt out of posix acl caching. Commit facd61053cff1 ("fuse: fixes after adapting to new posix acl api") used this facility to opt out of posix acl caching for fuse inodes with fuse server that does not negotiate FUSE_POSIX_ACL (fc->posix_acl). The commit also takes care to gate the forget_all_cached_acls() call in fuse_set_acl() on fc->posix_acl because there is no need for it, but there are other placed in fuse code which call forget_all_cached_acls() unconditional to fc->posix_acl and those cause the loss of the ACL_DONT_CACHE state. This is not only a functional bug. Properly timed, a get_acl() from this fuse filesystem can return a stale cached value, as was observed in tests, because set_acl() does not invalidate the unintentional acl cache. We could fix this in fuse, but it actually makes no sense for the vfs helper forget_cached_acl() to invalidate the ACL_DONT_CACHE state, so let it not do that to fix fuse and future users of ACL_DONT_CACHE.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Synchronization
The product utilizes multiple threads, processes, components, or systems to allow temporary access to a shared resource that can only be exclusive to one process at a time, but it does not properly synchronize these actions, which might cause simultaneous accesses of this resource by multiple threads or processes.
How developers prevent this class of flaw
- Use industry standard APIs to synchronize your code.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other references
- git.kernel.org/stable/c/4b9a5458d02e214ef2b384124ca626e3e381d778
- git.kernel.org/stable/c/834ddf899484a2f23129080e8773bc04f4691d07
- git.kernel.org/stable/c/a019b074903b3ad0a9726087efd0e8291452023b
- git.kernel.org/stable/c/b98fad81f1202b0eb26aacf3ff4cc7a21ed3b5bf
- git.kernel.org/stable/c/ca03a7984a34f48085fd013e0d2cf4e6420b4acf
Recent Improper Synchronization vulnerabilities
- 7.8 High severity
- 7.1 High severity
- 7.8 High severity
- 7.5 High severity
- 8.8 High severity
- 8.2 High severity
Spotted an error? Tell us.