Linux: Integer Overflow or Wraparound
CVE-2026-31633 is a critical-severity integer overflow or wraparound vulnerability in Linux, with a CVSS 3.1 base score of 9.8 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 1f864d9daaf622aeaa774404fd51e7d6a435b046, c1e242beb6b1efc3c286f617e8d940c8fbf2ed41, 699e52180f4231c257821c037ed5c99d5eb0edb8 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.
Critical severity: a successful attack would have severe impact.
What to do
- Update Linux to 1f864d9daaf622aeaa774404fd51e7d6a435b046 or c1e242beb6b1efc3c286f617e8d940c8fbf2ed41 or 699e52180f4231c257821c037ed5c99d5eb0edb8, 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 | 9d1d2b59341f58126a69b51f9f5f8ccb9f12e54a up to, but not including, 1f864d9daaf622aeaa774404fd51e7d6a435b046; 9d1d2b59341f58126a69b51f9f5f8ccb9f12e54a up to, but not including, c1e242beb6b1efc3c286f617e8d940c8fbf2ed41; 9d1d2b59341f58126a69b51f9f5f8ccb9f12e54a up to, but not including, 699e52180f4231c257821c037ed5c99d5eb0edb8; 6.16 | 1f864d9daaf622aeaa774404fd51e7d6a435b046, c1e242beb6b1efc3c286f617e8d940c8fbf2ed41, 699e52180f4231c257821c037ed5c99d5eb0edb8 |
| 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
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: rxrpc: Fix integer overflow in rxgk_verify_response() In rxgk_verify_response(), there's a potential integer overflow due to rounding up token_len before checking it, thereby allowing the length check to be bypassed. Fix this by checking the unrounded value against len too (len is limited as the response must fit in a single UDP packet).
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Integer Overflow or Wraparound
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
How developers prevent this class of flaw
- Ensure that all protocols are strictly defined, such that all out-of-bounds behavior can be identified simply, and require strict conformance to the protocol.
- Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. If possible, choose a language or compiler that performs automatic bounds checking.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Use libraries or frameworks that make it easier to handle numbers without unexpected consequences. Examples include safe integer handling packages such as SafeInt (C++) or IntegerLib (C or C++).
More Integer Overflow or Wraparound vulnerabilities (CWE-190)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Recent Integer Overflow or Wraparound vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 7.8 High severity
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