NFSv4: include MAY_WRITE in open permission mask for O_TRUNC
Summary
| CVE | CVE-2026-64298 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-07-25 10:17:10 UTC |
| Updated | 2026-07-25 10:17:10 UTC |
| 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. |
Risk And Classification
EPSS: 0.002200000 probability, percentile 0.125980000 (date 2026-07-25)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected af22f94ae02ab9dd4fd7fe628c8434a59cc293be 4817c8974315b666e895b7d1bb83cd3664c323b1 git | Not specified |
| CNA | Linux | Linux | affected af22f94ae02ab9dd4fd7fe628c8434a59cc293be cb148a2762d644bff1894728e8835a9a4b84f9ea git | Not specified |
| CNA | Linux | Linux | affected af22f94ae02ab9dd4fd7fe628c8434a59cc293be 30fdf4df6c3c00efec947e4ddf97f0fdd4473628 git | Not specified |
| CNA | Linux | Linux | affected af22f94ae02ab9dd4fd7fe628c8434a59cc293be 22c1fd1355ad4ca27aa7f0fa02719122dd92d9de git | Not specified |
| CNA | Linux | Linux | affected af22f94ae02ab9dd4fd7fe628c8434a59cc293be 6bd7d0a06b53c4e797e1a9cea0d2d41aa1b26230 git | Not specified |
| CNA | Linux | Linux | affected af22f94ae02ab9dd4fd7fe628c8434a59cc293be a937e92c1d00534b5c2e3e9f4381b7e988180797 git | Not specified |
| CNA | Linux | Linux | affected af22f94ae02ab9dd4fd7fe628c8434a59cc293be e36501b7d4abdcd6d69a7cb901b2f286b7a3d041 git | Not specified |
| CNA | Linux | Linux | affected af22f94ae02ab9dd4fd7fe628c8434a59cc293be 5140f099ecd8a2f2808b7f7b720ee1bad8468974 git | Not specified |
| CNA | Linux | Linux | affected 2.6.24 | Not specified |
| CNA | Linux | Linux | unaffected 2.6.24 semver | Not specified |
| CNA | Linux | Linux | unaffected 5.10.261 5.10.* semver | Not specified |
| CNA | Linux | Linux | unaffected 5.15.212 5.15.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.1.178 6.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.6.145 6.6.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.12.96 6.12.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.18.39 6.18.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.1.4 7.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.2-rc3 * original_commit_for_fix | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/cb148a2762d644bff1894728e8835a9a4b84f9ea | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/6bd7d0a06b53c4e797e1a9cea0d2d41aa1b26230 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/a937e92c1d00534b5c2e3e9f4381b7e988180797 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/e36501b7d4abdcd6d69a7cb901b2f286b7a3d041 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/4817c8974315b666e895b7d1bb83cd3664c323b1 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/22c1fd1355ad4ca27aa7f0fa02719122dd92d9de | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/5140f099ecd8a2f2808b7f7b720ee1bad8468974 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/30fdf4df6c3c00efec947e4ddf97f0fdd4473628 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.