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VulnerabilityPublished Updated

CVE-2026-64298: Linux kernel · Missing Authorization

Source GCVE Database

0
Authoritative record:CVE-2026-64298· High 7.1

Not known to be exploited · CVSS 7.1 High · fixed in e36501b7d4abdcd6d69a7cb901b2f286b7a3d041 : patch Linux kernel soon.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score
7.1High
How severe the flaw is on the 0–10 CVSS scale.
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.
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:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 25 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ af22f94ae02ab9dd4fd7fe628c8434a59cc293be, < e36501b7d4abdcd6d69a7cb901b2f286b7a3d041
Fixed in
  • e36501b7d4abdcd6d69a7cb901b2f286b7a3d041
LinuxLinuxAffected
  • ≥ af22f94ae02ab9dd4fd7fe628c8434a59cc293be, < cb148a2762d644bff1894728e8835a9a4b84f9ea
Fixed in
  • cb148a2762d644bff1894728e8835a9a4b84f9ea
LinuxLinuxAffected
  • ≥ af22f94ae02ab9dd4fd7fe628c8434a59cc293be, < a937e92c1d00534b5c2e3e9f4381b7e988180797
Fixed in
  • a937e92c1d00534b5c2e3e9f4381b7e988180797
LinuxLinuxAffected
  • ≥ af22f94ae02ab9dd4fd7fe628c8434a59cc293be, < 5140f099ecd8a2f2808b7f7b720ee1bad8468974
Fixed in
  • 5140f099ecd8a2f2808b7f7b720ee1bad8468974
LinuxLinuxAffected
  • ≥ af22f94ae02ab9dd4fd7fe628c8434a59cc293be, < 4817c8974315b666e895b7d1bb83cd3664c323b1
Fixed in
  • 4817c8974315b666e895b7d1bb83cd3664c323b1
LinuxLinuxAffected
  • ≥ af22f94ae02ab9dd4fd7fe628c8434a59cc293be, < 30fdf4df6c3c00efec947e4ddf97f0fdd4473628
Fixed in
  • 30fdf4df6c3c00efec947e4ddf97f0fdd4473628

AI-suggested

A fix has been implemented in the Linux kernel to include write permission in the open permission mask when O_TRUNC is used. Users should apply the official kernel updates that contain this fix. Since this is a kernel-level issue, updating to a patched kernel version is the recommended remediation. Patch status is not explicitly confirmed here; users should consult the Linux kernel vendor advisory for the specific fixed versions and update accordingly.

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

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