CVE-2026-31696: rxrpc: Fix missing validation of ticket length in non-XDR key preparsing
Vulnerability summary
CVE-2026-31696 is a high (CVSS 7.8) Out-of-bounds Write vulnerability in linux. EPSS estimates a 0.14% chance of exploitation in the next 30 days, higher than 2.9% of scored vulnerabilities.
Not severe (CVSS 7.8, local access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 35 · Related 34Timeline
- 01-05-2026PublishedVulnerability first disclosed.
- 15-10-2026Last modifiedVulnerability information updated.
Description
In the Linux kernel, the following vulnerability has been resolved: rxrpc: Fix missing validation of ticket length in non-XDR key preparsing In rxrpc_preparse(), there are two paths for parsing key payloads: the XDR path (for large payloads) and the non-XDR path (for payloads <= 28 bytes). While the XDR path (rxrpc_preparse_xdr_rxkad()) correctly validates the ticket length against AFSTOKEN_RK_TIX_MAX, the non-XDR path fails to do so. This allows an unprivileged user to provide a very large ticket length. When this key is later read via rxrpc_read(), the total token size (toksize) calculation results in a value that exceeds AFSTOKEN_LENGTH_MAX, triggering a WARN_ON(). [ 2001.302904] WARNING: CPU: 2 PID: 2108 at net/rxrpc/key.c:778 rxrpc_read+0x109/0x5c0 [rxrpc] Fix this by adding a check in the non-XDR parsing path of rxrpc_preparse() to ensure the ticket length does not exceed AFSTOKEN_RK_TIX_MAX, bringing it into parity with the XDR parsing logic.
CVSS metrics
4 scores · 3 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated7.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- OSV · DebianEcosystem advisory · calculated7.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS trend
Probability
0.14%
Chance of exploitation in the next 30 days
Percentile
3%
Versus all other CVEs
30-day change
Decrease -0.04 pp
From 0.18% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu158 products
- linuxAll versions (No fix recorded) | < 5.15.0-186.196 | < 6.8.0-136.136 | < 7.0.0-27.27
- linux-allwinner-5.19All versions (No fix recorded)
- linux-awsAll versions (No fix recorded) | < 5.15.0-1112.119 | < 6.8.0-1061.64 | < 7.0.0-1008.8
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Chainguard6 products
- linux-aws-6.18< 6.18.31-r0
- linux-azure-6.18< 6.18.24-r1 | < 6.18.31-r0
- linux-gcp-6.18< 6.18.31-r0
- linux-qemu-6.18< 6.18.24-r3
- linux-qemu-rc< 7.1_rc3-r0
Linux2 products
- linux≥ 8a7a3eb4ddbe7c7e639170a64adede7cbd5a9247, < 44714dfda386884919ba366411880b6fb3c3efd3 | ≥ 8a7a3eb4ddbe7c7e639170a64adede7cbd5a9247, < 41a117dd80371343babc52198d1114e83eb37627 | ≥ 8a7a3eb4ddbe7c7e639170a64adede7cbd5a9247, < 9a397aa9b5e53ca63d4d6aefb542832eca389618 | ≥ 8a7a3eb4ddbe7c7e639170a64adede7cbd5a9247, < 1fa36cf495b0023e8475d038535c05e4063211e1 | ≥ 8a7a3eb4ddbe7c7e639170a64adede7cbd5a9247, < 4458757c020592a3094366e0fb20457383b42f92 | ≥ 8a7a3eb4ddbe7c7e639170a64adede7cbd5a9247, < ce383ba615339f8eaec646a166d2c2b015bb5ca0 | ≥ 8a7a3eb4ddbe7c7e639170a64adede7cbd5a9247, < a1be1c9ece26cea69654f28b255ff9a7906b897b | ≥ 8a7a3eb4ddbe7c7e639170a64adede7cbd5a9247, < ac33733b10b484d666f97688561670afd5861383 | 3.17
- linux_kernel≥ 3.17, < 6.6.136 | ≥ 6.7, < 6.12.84 | ≥ 6.13, < 6.18.25 | ≥ 6.19, < 7.0.2 | 7.1:rc1 | 7.1:rc2
Debian1 product
- linux< 6.1.176-1 | < 6.12.85-1 | < 7.0.3-1
4 vendors · 167 products
