CyberSecBulletin
CVE-2026-31635NVD status: Modified

Linux: Improper Handling of Length Parameter Inconsistency

Published Updated By the CyberSecBulletin desk

CVE-2026-31635 is a high-severity improper handling of length parameter inconsistency 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 beee051f259acd286fed64c32c2b31e6f5097eb5, e2f1a80d8b1ed6a5ae585a399c2b46500bdcc305, a2567217ade970ecc458144b6be469bc015b23e5 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 1.13% chance of exploitation within 30 days, higher than 67% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to beee051f259acd286fed64c32c2b31e6f5097eb5 or e2f1a80d8b1ed6a5ae585a399c2b46500bdcc305 or a2567217ade970ecc458144b6be469bc015b23e5, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 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
LinuxLinux9d1d2b59341f58126a69b51f9f5f8ccb9f12e54a up to, but not including, beee051f259acd286fed64c32c2b31e6f5097eb5; 9d1d2b59341f58126a69b51f9f5f8ccb9f12e54a up to, but not including, e2f1a80d8b1ed6a5ae585a399c2b46500bdcc305; 9d1d2b59341f58126a69b51f9f5f8ccb9f12e54a up to, but not including, a2567217ade970ecc458144b6be469bc015b23e5; 6.16beee051f259acd286fed64c32c2b31e6f5097eb5, e2f1a80d8b1ed6a5ae585a399c2b46500bdcc305, a2567217ade970ecc458144b6be469bc015b23e5
LinuxLinux Kernel6.16.1 up to, but not including, 6.18.23; 6.19 up to, but not including, 6.19.13; 6.16; 7.06.18.23, 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 oversized RESPONSE authenticator length check rxgk_verify_response() decodes auth_len from the packet and is supposed to verify that it fits in the remaining bytes. The existing check is inverted, so oversized RESPONSE authenticators are accepted and passed to rxgk_decrypt_skb(), which can later reach skb_to_sgvec() with an impossible length and hit BUG_ON(len). Decoded from the original latest-net reproduction logs with scripts/decode_stacktrace.sh: RIP: __skb_to_sgvec() [net/core/skbuff.c:5285 (discriminator 1)] Call Trace: skb_to_sgvec() [net/core/skbuff.c:5305] rxgk_decrypt_skb() [net/rxrpc/rxgk_common.h:81] rxgk_verify_response() [net/rxrpc/rxgk.c:1268] rxrpc_process_connection() [net/rxrpc/conn_event.c:266 net/rxrpc/conn_event.c:364 net/rxrpc/conn_event.c:386] process_one_work() [kernel/workqueue.c:3281] worker_thread() [kernel/workqueue.c:3353 kernel/workqueue.c:3440] kthread() [kernel/kthread.c:436] ret_from_fork() [arch/x86/kernel/process.c:164] Reject authenticator lengths that exceed the remaining packet payload.

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

The underlying weakness: Improper Handling of Length Parameter Inconsistency

The product parses a formatted message or structure, but it does not handle or incorrectly handles a length field that is inconsistent with the actual length of the associated data.

How developers prevent this class of flaw

  • When processing structured incoming data containing a size field followed by raw data, ensure that you identify and resolve any inconsistencies between the size field and the actual size of the data.
  • Do not let the user control the size of the buffer.
  • Validate that the length of the user-supplied data is consistent with the buffer size.

More Improper Handling of Length Parameter Inconsistency vulnerabilities (CWE-130)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Improper Handling of Length Parameter Inconsistency vulnerabilities

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