Linux: Missing Release of Memory after Effective Lifetime
CVE-2026-31640 is a high-severity missing release of memory after effective lifetime 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 9132b1a7bf83b4a8042fffbc99d075b727a16742, 20386e7f8d97475b8d815873e246423317ec4260, b33f5741bb187db8ff32e8f5b96def77cc94dfca 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 0.43% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to 9132b1a7bf83b4a8042fffbc99d075b727a16742 or 20386e7f8d97475b8d815873e246423317ec4260 or b33f5741bb187db8ff32e8f5b96def77cc94dfca, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.18.23 or 6.19.13, whichever matches your release line, or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 5800b1cf3fd8ccab752a101865be1e76dac33142 up to, but not including, 9132b1a7bf83b4a8042fffbc99d075b727a16742; 5800b1cf3fd8ccab752a101865be1e76dac33142 up to, but not including, 20386e7f8d97475b8d815873e246423317ec4260; 5800b1cf3fd8ccab752a101865be1e76dac33142 up to, but not including, b33f5741bb187db8ff32e8f5b96def77cc94dfca; 6.16 | 9132b1a7bf83b4a8042fffbc99d075b727a16742, 20386e7f8d97475b8d815873e246423317ec4260, b33f5741bb187db8ff32e8f5b96def77cc94dfca |
| Linux | Linux Kernel | 6.16.1 up to, but not including, 6.18.23; 6.19 up to, but not including, 6.19.13; 6.16; 7.0 | 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: Fix use of wrong skb when comparing queued RESP challenge serial In rxrpc_post_response(), the code should be comparing the challenge serial number from the cached response before deciding to switch to a newer response, but looks at the newer packet private data instead, rendering the comparison always false. Fix this by switching to look at the older packet. Fix further[1] to substitute the new packet in place of the old one if newer and also to release whichever we don't use.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Missing Release of Memory after Effective Lifetime
The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.
How developers prevent this class of flaw
- Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone. For example, glibc in Linux provides protection against free of invalid pointers. When using Xcode to target OS X or iOS, enable automatic reference counting (ARC). To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std
- Use an abstraction library to abstract away risky APIs. Not a complete solution.
- Consider using the Boehm-Demers-Weiser garbage collector (bdwgc), which can help avoid leaks.
More Missing Release of Memory after Effective Lifetime vulnerabilities (CWE-401)
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Recent Missing Release of Memory after Effective Lifetime vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 8.6 High severity
- 7.5 High severity
- 7.8 High severity
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