CyberSecBulletin
CVE-2026-31676NVD status: Modified

Linux: Concurrent Execution using Shared Resource with Improper Synchronization

Published Updated By the CyberSecBulletin desk

CVE-2026-31676 is a high-severity concurrent execution using shared resource with improper synchronization 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 a1a8efde03a40b6c658d580e96644d9b9a2a0d3a, 6c3a0fbdafef8316e34ae22333e317a341e737cd, 0afdfd4941c1b60a1f5c361760daa970edca60cd 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 0.47% 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 a1a8efde03a40b6c658d580e96644d9b9a2a0d3a or 6c3a0fbdafef8316e34ae22333e317a341e737cd or 0afdfd4941c1b60a1f5c361760daa970edca60cd or a6bcf8010af093fe04f7100562e9542ab7882585, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.6.136 or 6.12.84 or 6.18.23 or 6.19.13, 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
LinuxLinux17926a79320afa9b95df6b977b40cca6d8713cea up to, but not including, a1a8efde03a40b6c658d580e96644d9b9a2a0d3a; 17926a79320afa9b95df6b977b40cca6d8713cea up to, but not including, 6c3a0fbdafef8316e34ae22333e317a341e737cd; 17926a79320afa9b95df6b977b40cca6d8713cea up to, but not including, 0afdfd4941c1b60a1f5c361760daa970edca60cd; 17926a79320afa9b95df6b977b40cca6d8713cea up to, but not including, a6bcf8010af093fe04f7100562e9542ab7882585; 17926a79320afa9b95df6b977b40cca6d8713cea up to, but not including, 29b44d904dceb832be880def08b8cb17a0aba91c; 17926a79320afa9b95df6b977b40cca6d8713cea up to, but not including, d0035e634dae83237ab7f5681eb52b2f65d0ceb8; 17926a79320afa9b95df6b977b40cca6d8713cea up to, but not including, 03fd2ef73cb4ffd0af100a95b634af54f474414e; 17926a79320afa9b95df6b977b40cca6d8713cea up to, but not including, c43ffdcfdbb5567b1f143556df8a04b4eeea041c; and 1 more rangesa1a8efde03a40b6c658d580e96644d9b9a2a0d3a, 6c3a0fbdafef8316e34ae22333e317a341e737cd, 0afdfd4941c1b60a1f5c361760daa970edca60cd, a6bcf8010af093fe04f7100562e9542ab7882585, 29b44d904dceb832be880def08b8cb17a0aba91c, d0035e634dae83237ab7f5681eb52b2f65d0ceb8
SiemensSIMATIC S7-1500 TM MFP - GNU/Linux subsystemall versionsNot stated
LinuxLinux Kernel2.6.22 up to, but not including, 6.6.136; 6.7 up to, but not including, 6.12.84; 6.13 up to, but not including, 6.18.23; 6.19 up to, but not including, 6.19.13; 7.06.6.136, 6.12.84, 6.18.23, 6.19.13

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: rxrpc: only handle RESPONSE during service challenge Only process RESPONSE packets while the service connection is still in RXRPC_CONN_SERVICE_CHALLENGING. Check that state under state_lock before running response verification and security initialization, then use a local secured flag to decide whether to queue the secured-connection work after the state transition. This keeps duplicate or late RESPONSE packets from re-running the setup path and removes the unlocked post-transition state test.

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

The underlying weakness: Concurrent Execution using Shared Resource with Improper Synchronization

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.

How developers prevent this class of flaw

  • In languages that support it, use synchronization primitives. Only wrap these around critical code to minimize the impact on performance.
  • Use thread-safe capabilities such as the data access abstraction in Spring.
  • Minimize the usage of shared resources in order to remove as much complexity as possible from the control flow and to reduce the likelihood of unexpected conditions occurring. Additionally, this will minimize the amount of synchronization necessary and may even help to reduce the likelihood of a denial of service where an attacker may be able to repeatedly trigger a critical section (CWE-400).

More Concurrent Execution using Shared Resource with Improper Synchronization vulnerabilities (CWE-362)

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 Concurrent Execution using Shared Resource with Improper Synchronization vulnerabilities

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