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🛡️ CVE-2026-31684 — kernel

🟡 CVSS 5.5 — Medium ✅ No Known Exploit NVD
5.5
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

net: sched: act_csum: validate nested VLAN headers

In the Linux kernel, the following vulnerability has been resolved:

net: sched: act_csum: validate nested VLAN headers

tcf_csum_act() walks nested VLAN headers directly from skb->data when an

skb still carries in-payload VLAN tags. The current code reads

vlan->h_vlan_encapsulated_proto and then pulls VLAN_HLEN bytes without

first ensuring that the full VLAN header is present in the linear area.

If only part of an inner VLAN header is linearized, accessing

h_vlan_encapsulated_proto reads past the linear area, and the following

skb_pull(VLAN_HLEN) may violate skb invariants.

Fix this by requiring pskb_may_pull(skb, VLAN_HLEN) before accessing and

pulling each nested VLAN header. If the header still is not fully

available, drop the packet through the existing error path.

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

Affected software

CVE-2026-31684 is recorded against 2 packages.

  • kernel (from 6.19.0 up to 6.19.14)
  • linux-kernel

Timeline and source

Published on 25 April 2026 and last revised on 12 August 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
github.com (Advisory)
nvd.nist.gov (Advisory)
git.kernel.org (Package)

CVE-2026-31684 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity Medium
CVSS Score 5.5
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CWE N/A
Public Exploit ✅ No
Source NVD
Published 2026-04-25
Updated 2026-08-20
Modified 2026-08-12

Affected Packages

Software From version Fixed in
kernel 6.19.0 6.19.14
linux-kernel — —

References

Similar Threats

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