CyberSecBulletin
CVE-2026-53391NVD status: Modified

Linux: NULL Pointer Dereference

Published Updated By the CyberSecBulletin desk

CVE-2026-53391 is a high-severity NULL pointer dereference vulnerability in Linux, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 76b94cbd32aacf36a641956385a852635c6802b9, c8e4e0c701d0192a2efb6df059c0f9e19678c23d, 6c344fff2feff9d4d716d8e4ad40e9b5040ee5ea 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 0.52% 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 76b94cbd32aacf36a641956385a852635c6802b9 or c8e4e0c701d0192a2efb6df059c0f9e19678c23d or 6c344fff2feff9d4d716d8e4ad40e9b5040ee5ea or 427ab81a811dab4bca9d19f82eec5847ae42646e, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.15.211 or 6.1.177 or 6.6.144 or 6.12.95, whichever matches your release line, or a later version.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux6b7f3cf96364eaf597940cb5c68a682894829915 up to, but not including, 76b94cbd32aacf36a641956385a852635c6802b9; 6b7f3cf96364eaf597940cb5c68a682894829915 up to, but not including, c8e4e0c701d0192a2efb6df059c0f9e19678c23d; 6b7f3cf96364eaf597940cb5c68a682894829915 up to, but not including, 6c344fff2feff9d4d716d8e4ad40e9b5040ee5ea; 6b7f3cf96364eaf597940cb5c68a682894829915 up to, but not including, 427ab81a811dab4bca9d19f82eec5847ae42646e; 6b7f3cf96364eaf597940cb5c68a682894829915 up to, but not including, 012d37a568bfbb2c9686f03ade75560bc7139956; 6b7f3cf96364eaf597940cb5c68a682894829915 up to, but not including, 30aae62e50b4e074a90a9a5e15246548fbdc1182; 6b7f3cf96364eaf597940cb5c68a682894829915 up to, but not including, 41fe0f7b84f0cb822ae10ab08592996a592b2a25; 4.076b94cbd32aacf36a641956385a852635c6802b9, c8e4e0c701d0192a2efb6df059c0f9e19678c23d, 6c344fff2feff9d4d716d8e4ad40e9b5040ee5ea, 427ab81a811dab4bca9d19f82eec5847ae42646e, 012d37a568bfbb2c9686f03ade75560bc7139956, 30aae62e50b4e074a90a9a5e15246548fbdc1182
LinuxLinux Kernel4.0 up to, but not including, 5.15.211; 5.16 up to, but not including, 6.1.177; 6.2 up to, but not including, 6.6.144; 6.7 up to, but not including, 6.12.95; 6.13 up to, but not including, 6.18.38; 6.19 up to, but not including, 7.1.35.15.211, 6.1.177, 6.6.144, 6.12.95, 6.18.38, 7.1.3

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
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
NoneNo data is disclosed.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

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

Official description

In the Linux kernel, the following vulnerability has been resolved: NFSv4/pNFS: reject zero-length r_addr in nfs4_decode_mp_ds_addr nfs4_decode_mp_ds_addr() decodes the r_netid and r_addr opaques of a netaddr4 from a GETDEVICEINFO multipath-DS body, then immediately calls strrchr(buf, '.') to locate the port separator. Both decodes use xdr_stream_decode_string_dup(), and the current code checks only "nlen < 0" / "rlen < 0" before dereferencing the returned string. When the on-wire opaque has length zero, xdr_stream_decode_opaque_inline() returns 0 and xdr_stream_decode_string_dup() falls through to its "*str = NULL; return ret" tail, leaving buf NULL with a return value of 0. The "< 0" check does not catch this, and the next line is strrchr(NULL, '.'), a kernel NULL pointer dereference reachable from any pNFS-flexfile client mounted against a malicious or compromised metadata server. Reject the zero-length cases explicitly so the decoder fails with -EBADMSG (treated as a malformed GETDEVICEINFO body) instead of panicking the client.

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

The underlying weakness: NULL Pointer Dereference

The product dereferences a pointer that it expects to be valid but is NULL.

How developers prevent this class of flaw

  • For any pointers that could have been modified or provided from a function that can return NULL, check the pointer for NULL before use. When working with a multithreaded or otherwise asynchronous environment, ensure that proper locking APIs are used to lock before the check, and unlock when it has finished.
  • Select a programming language that is not susceptible to these issues.
  • Check the results of all functions that return a value and verify that the value is non-null before acting upon it.

More NULL Pointer Dereference vulnerabilities (CWE-476)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Recent NULL Pointer Dereference vulnerabilities

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