CyberSecBulletin
CVE-2026-64298NVD status: Modified

Linux: Missing Authorization

Published Updated By the CyberSecBulletin desk

CVE-2026-64298 is a high-severity missing authorization vulnerability in Linux, with a CVSS 3.1 base score of 7.1 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 4817c8974315b666e895b7d1bb83cd3664c323b1, cb148a2762d644bff1894728e8835a9a4b84f9ea, 30fdf4df6c3c00efec947e4ddf97f0fdd4473628 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.15% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 4817c8974315b666e895b7d1bb83cd3664c323b1 or cb148a2762d644bff1894728e8835a9a4b84f9ea or 30fdf4df6c3c00efec947e4ddf97f0fdd4473628 or 22c1fd1355ad4ca27aa7f0fa02719122dd92d9de, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.261 or 5.15.212 or 6.1.178 or 6.6.145, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxaf22f94ae02ab9dd4fd7fe628c8434a59cc293be up to, but not including, 4817c8974315b666e895b7d1bb83cd3664c323b1; af22f94ae02ab9dd4fd7fe628c8434a59cc293be up to, but not including, cb148a2762d644bff1894728e8835a9a4b84f9ea; af22f94ae02ab9dd4fd7fe628c8434a59cc293be up to, but not including, 30fdf4df6c3c00efec947e4ddf97f0fdd4473628; af22f94ae02ab9dd4fd7fe628c8434a59cc293be up to, but not including, 22c1fd1355ad4ca27aa7f0fa02719122dd92d9de; af22f94ae02ab9dd4fd7fe628c8434a59cc293be up to, but not including, 6bd7d0a06b53c4e797e1a9cea0d2d41aa1b26230; af22f94ae02ab9dd4fd7fe628c8434a59cc293be up to, but not including, a937e92c1d00534b5c2e3e9f4381b7e988180797; af22f94ae02ab9dd4fd7fe628c8434a59cc293be up to, but not including, e36501b7d4abdcd6d69a7cb901b2f286b7a3d041; af22f94ae02ab9dd4fd7fe628c8434a59cc293be up to, but not including, 5140f099ecd8a2f2808b7f7b720ee1bad8468974; and 1 more ranges4817c8974315b666e895b7d1bb83cd3664c323b1, cb148a2762d644bff1894728e8835a9a4b84f9ea, 30fdf4df6c3c00efec947e4ddf97f0fdd4473628, 22c1fd1355ad4ca27aa7f0fa02719122dd92d9de, 6bd7d0a06b53c4e797e1a9cea0d2d41aa1b26230, a937e92c1d00534b5c2e3e9f4381b7e988180797
LinuxLinux Kernel2.6.24 up to, but not including, 5.10.261; 5.11 up to, but not including, 5.15.212; 5.16 up to, but not including, 6.1.178; 6.2 up to, but not including, 6.6.145; 6.7 up to, but not including, 6.12.96; 6.13 up to, but not including, 6.18.39; 6.19 up to, but not including, 7.1.4; 7.25.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.96, 6.18.39

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
NoneNo data is disclosed.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H. Scored by CNA.

Official 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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Missing Authorization

The product does not perform an authorization check when an actor attempts to access a resource or perform an action.

How developers prevent this class of flaw

  • Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) to enforce the roles at the appropriate boundaries. Note that this approach may not protect against horizontal authorization, i.e., it will not protect a user from attacking others with the same role.
  • Ensure that access control checks are performed related to the business logic. These checks may be different than the access control checks that are applied to more generic resources such as files, connections, processes, memory, and database records. For example, a database may restrict access for medical records to a specific database user, but each record might only be intended to be accessible to the patient and the patient's doctor.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using authorization frameworks such as the JAAS Authorization Framework and the OWASP ESAPI Access Control feature.

More Missing Authorization vulnerabilities (CWE-862)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Missing Authorization vulnerabilities

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