CVE-2026-64298NFSv4: include MAY_WRITE in open permission mask for O_TRUNC
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 7.1 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Analyzed
- Record last updated
- Oct 16, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from af22f94ae02ab9dd4fd7fe628c8434a59cc293be before 4817c8974315b666e895b7d1bb83cd3664c323b1; from af22f94ae02ab9dd4fd7fe628c8434a59cc293be before cb148a2762d644bff1894728e8835a9a4b84f9ea; from af22f94ae02ab9dd4fd7fe628c8434a59cc293be before 30fdf4df6c3c00efec947e4ddf97f0fdd4473628; from af22f94ae02ab9dd4fd7fe628c8434a59cc293be before 22c1fd1355ad4ca27aa7f0fa02719122dd92d9de; from af22f94ae02ab9dd4fd7fe628c8434a59cc293be before 6bd7d0a06b53c4e797e1a9cea0d2d41aa1b26230; from af22f94ae02ab9dd4fd7fe628c8434a59cc293be before a937e92c1d00534b5c2e3e9f4381b7e988180797; from af22f94ae02ab9dd4fd7fe628c8434a59cc293be before e36501b7d4abdcd6d69a7cb901b2f286b7a3d041; from af22f94ae02ab9dd4fd7fe628c8434a59cc293be before 5140f099ecd8a2f2808b7f7b720ee1bad8468974 | CNA record |
linux linux_kernel linux:linux_kernel | from 2.6.24 before 5.10.261; from 5.11 before 5.15.212; from 5.16 before 6.1.178; from 6.2 before 6.6.145; from 6.7 before 6.12.96; from 6.13 before 6.18.39; from 6.19 before 7.1.4; 7.2; and 1 more ranges | NVD |
References
- https://git.kernel.org/stable/c/4817c8974315b666e895b7d1bb83cd3664c323b1patch
- https://git.kernel.org/stable/c/cb148a2762d644bff1894728e8835a9a4b84f9eapatch
- https://git.kernel.org/stable/c/30fdf4df6c3c00efec947e4ddf97f0fdd4473628patch
- https://git.kernel.org/stable/c/22c1fd1355ad4ca27aa7f0fa02719122dd92d9depatch
- https://git.kernel.org/stable/c/6bd7d0a06b53c4e797e1a9cea0d2d41aa1b26230patch
- https://git.kernel.org/stable/c/a937e92c1d00534b5c2e3e9f4381b7e988180797patch
- https://git.kernel.org/stable/c/e36501b7d4abdcd6d69a7cb901b2f286b7a3d041patch
- https://git.kernel.org/stable/c/5140f099ecd8a2f2808b7f7b720ee1bad8468974patch
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.