CVE-2026-64298
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.
Affected versions
Linux kernel versions
2.6.24
and later are affected. Fixed in
5.10.261,
5.15.212,
6.1.178,
6.6.145,
6.12.96,
6.18.39,
7.1.4,
7.2-rc3
and their respective stable series.
References
8 totalFrequently asked questions
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What is CVE-2026-64298?
CVE-2026-64298 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 2.6.24 onward and has been patched in 5.10.261, 5.15.212, 6.1.178 and others. CVE-2026-64298 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
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Is there a patch available for CVE-2026-64298?
Yes. CVE-2026-64298 has been patched. Fixed versions include 5.10.261, 5.15.212, 6.1.178 and others. If you are running Linux kernel 2.6.24 or later up to the fix versions, apply the relevant patch for your kernel branch.
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Is CVE-2026-64298 actively exploited?
No. CVE-2026-64298 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.