CVE-2026-64298: Linux kernel · Missing Authorization
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 7.1 High · fixed in e36501b7d4abdcd6d69a7cb901b2f286b7a3d041 : patch Linux kernel soon.
Data as of 26 Oct 2026, 13:47 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 3% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-10-16.
- Patch
- Available – fixed in e36501b7d4abdcd6d69a7cb901b2f286b7a3d041, cb148a2762d644bff1894728e8835a9a4b84f9ea, a937e92c1d00534b5c2e3e9f4381b7e988180797 +5
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 25 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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Description
In the Linux kernel, the following vulnerability has been resolved: NFSv4: include MAY_WRITE in open permission mask for O_TRUNC POSIX requires write permission to truncate a file, so an open() that specifies O_TRUNC must be authorized for write access regardless of the O_ACCMODE access mode. nfs_open_permission_mask() builds the access mask passed to nfs_may_open(), which is the local authorization gate for OPENs the client serves itself from a cached write delegation via the can_open_delegated() path in nfs4_try_open_cached(). The mask is derived from O_ACCMODE alone, so an open(O_RDONLY | O_TRUNC) against a file the caller cannot write requests only MAY_READ and passes the local check. The OPEN is then satisfied locally and the truncation is issued to the server as a SETATTR(size=0) over the delegation stateid, which the server accepts under standard write-delegation semantics. POSIX requires that this open fail with EACCES. Include MAY_WRITE in the mask whenever O_TRUNC is set so the local check matches the access the server would have enforced.
References
- git.kernel.org/stable/c/4817c8974315b666e895b7d1bb83cd3664c323b1 (opens in a new tab)
- git.kernel.org/stable/c/cb148a2762d644bff1894728e8835a9a4b84f9ea (opens in a new tab)
- git.kernel.org/stable/c/30fdf4df6c3c00efec947e4ddf97f0fdd4473628 (opens in a new tab)
- git.kernel.org/stable/c/22c1fd1355ad4ca27aa7f0fa02719122dd92d9de (opens in a new tab)
- git.kernel.org/stable/c/6bd7d0a06b53c4e797e1a9cea0d2d41aa1b26230 (opens in a new tab)
- git.kernel.org/stable/c/a937e92c1d00534b5c2e3e9f4381b7e988180797 (opens in a new tab)
- git.kernel.org/stable/c/e36501b7d4abdcd6d69a7cb901b2f286b7a3d041 (opens in a new tab)
- git.kernel.org/stable/c/5140f099ecd8a2f2808b7f7b720ee1bad8468974 (opens in a new tab)