CyberSecBulletin
CVE-2025-38566NVD status: Modified

Linux: Improper Check for Unusual or Exceptional Conditions

Published Updated By the CyberSecBulletin desk

CVE-2025-38566 is a high-severity improper check for unusual or exceptional conditions 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 b1df394621710b312f0393e3f240fdac0764f968, 25bb3647d30a20486b5fe7cff2b0e503c16c9692, 3b549da875414989f480b66835d514be80a0bd9c 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 0.67% chance of exploitation within 30 days, higher than 53% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to b1df394621710b312f0393e3f240fdac0764f968 or 25bb3647d30a20486b5fe7cff2b0e503c16c9692 or 3b549da875414989f480b66835d514be80a0bd9c or 6b33c31cc788073bfbed9297e1f4486ed73d87da, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.6.102 or 6.12.42 or 6.15.10 or 6.16.1, 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
LinuxLinux5e052dda121e2870dd87181783da4a95d7d2927b up to, but not including, b1df394621710b312f0393e3f240fdac0764f968; 5e052dda121e2870dd87181783da4a95d7d2927b up to, but not including, 25bb3647d30a20486b5fe7cff2b0e503c16c9692; 5e052dda121e2870dd87181783da4a95d7d2927b up to, but not including, 3b549da875414989f480b66835d514be80a0bd9c; 5e052dda121e2870dd87181783da4a95d7d2927b up to, but not including, 6b33c31cc788073bfbed9297e1f4486ed73d87da; 5e052dda121e2870dd87181783da4a95d7d2927b up to, but not including, bee47cb026e762841f3faece47b51f985e215edb; 6.4b1df394621710b312f0393e3f240fdac0764f968, 25bb3647d30a20486b5fe7cff2b0e503c16c9692, 3b549da875414989f480b66835d514be80a0bd9c, 6b33c31cc788073bfbed9297e1f4486ed73d87da, bee47cb026e762841f3faece47b51f985e215edb
LinuxLinux Kernel6.4 up to, but not including, 6.6.102; 6.7 up to, but not including, 6.12.42; 6.13 up to, but not including, 6.15.10; 6.16 up to, but not including, 6.16.1; 6.176.6.102, 6.12.42, 6.15.10, 6.16.1

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 NVD.

Scoring systemScoreSeverityScored by
CVSS 3.19.8CriticalCNA
CVSS 3.17.5HighNVD

Official description

In the Linux kernel, the following vulnerability has been resolved: sunrpc: fix handling of server side tls alerts Scott Mayhew discovered a security exploit in NFS over TLS in tls_alert_recv() due to its assumption it can read data from the msg iterator's kvec.. kTLS implementation splits TLS non-data record payload between the control message buffer (which includes the type such as TLS aler or TLS cipher change) and the rest of the payload (say TLS alert's level/description) which goes into the msg payload buffer. This patch proposes to rework how control messages are setup and used by sock_recvmsg(). If no control message structure is setup, kTLS layer will read and process TLS data record types. As soon as it encounters a TLS control message, it would return an error. At that point, NFS can setup a kvec backed msg buffer and read in the control message such as a TLS alert. Msg iterator can advance the kvec pointer as a part of the copy process thus we need to revert the iterator before calling into the tls_alert_recv.

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

The underlying weakness: Improper Check for Unusual or Exceptional Conditions

The product does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the product.

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Choose languages with features such as exception handling that force the programmer to anticipate unusual conditions that may generate exceptions. Custom exceptions may need to be developed to handle unusual business-logic conditions. Be careful not to pass sensitive exceptions back to the user (CWE-209, CWE-248).
  • Check the results of all functions that return a value and verify that the value is expected.
  • If using exception handling, catch and throw specific exceptions instead of overly-general exceptions (CWE-396, CWE-397). Catch and handle exceptions as locally as possible so that exceptions do not propagate too far up the call stack (CWE-705). Avoid unchecked or uncaught exceptions where feasible (CWE-248).

More Improper Check for Unusual or Exceptional Conditions vulnerabilities (CWE-754)

Timeline

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

References

Recent Improper Check for Unusual or Exceptional Conditions vulnerabilities

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