Medium 5.5Published Apr 25, 2026

CVE-2026-31684net: sched: act_csum: validate nested VLAN headers

Updated under an hour ago (Oct 28, 2026, 9:40 AM ET)

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Exploited in the last 30 days

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.

CVSS: 5.5 MEDIUM (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Modified
Record last updated: Jun 1, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from 2ecba2d1e45b24620a7c3df9531895cf68d5dec6 before 0410c619e86551677fb79887a38eccad3f5a0725; from 2ecba2d1e45b24620a7c3df9531895cf68d5dec6 before 886469b6455611a511aa6013e957e15e50577513; from 2ecba2d1e45b24620a7c3df9531895cf68d5dec6 before 46c07ad50fa2f4ba7663ee1b72b75ad7ad45cf09; from 2ecba2d1e45b24620a7c3df9531895cf68d5dec6 before eb3765b90eb8f2a3d6310a80c14a9e57ec4267a2; from 2ecba2d1e45b24620a7c3df9531895cf68d5dec6 before a69738efea0996d05a3c7d2178551b891744df1b; from 2ecba2d1e45b24620a7c3df9531895cf68d5dec6 before ec4930979b3f7bbeb7af5744599fc6603a4dba62; from 2ecba2d1e45b24620a7c3df9531895cf68d5dec6 before 3d165d975305cf76ff0b10a3c798fb31e5f5f9a5; from 2ecba2d1e45b24620a7c3df9531895cf68d5dec6 before c842743d073bdd683606cb414eb0ca84465dd834; and 2 more ranges	CNA record
linux linux_kernel linux:linux_kernel	from 4.19.99 before 4.20; from 5.1 before 6.6.136; from 6.7 before 6.12.83; from 6.13 before 6.18.24; from 6.19 before 6.19.14; 7.0; 7.0; 7.0; and 4 more ranges	NVD

References

References

https://git.kernel.org/stable/c/0410c619e86551677fb79887a38eccad3f5a0725
https://git.kernel.org/stable/c/886469b6455611a511aa6013e957e15e50577513
https://git.kernel.org/stable/c/46c07ad50fa2f4ba7663ee1b72b75ad7ad45cf09
https://git.kernel.org/stable/c/eb3765b90eb8f2a3d6310a80c14a9e57ec4267a2	patch
https://git.kernel.org/stable/c/a69738efea0996d05a3c7d2178551b891744df1b	patch
https://git.kernel.org/stable/c/ec4930979b3f7bbeb7af5744599fc6603a4dba62	patch
https://git.kernel.org/stable/c/3d165d975305cf76ff0b10a3c798fb31e5f5f9a5	patch
https://git.kernel.org/stable/c/c842743d073bdd683606cb414eb0ca84465dd834	patch

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.