CVE-2026-31684: net: sched: act_csum: validate nested VLAN headers
Vulnerability summary
CVE-2026-31684 is a medium (CVSS 5.5) vulnerability in linux. EPSS estimates a 0.12% chance of exploitation in the next 30 days, higher than 1.6% of scored vulnerabilities.
Not severe (CVSS 5.5, local access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 43 · Related 30Timeline
- 25-04-2026PublishedVulnerability first disclosed.
- 01-06-2026Last modifiedVulnerability information updated.
Description
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 metrics
3 scores · 3 sources · 1 version- OSV · UbuntuEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.12%
Chance of exploitation in the next 30 days
Percentile
2%
Versus all other CVEs
30-day change
Decrease -0.04 pp
From 0.16% 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 causeNo weakness data has been published for this record.
Affected systems
Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu153 products
- linuxAll versions (No fix recorded) | < 5.15.0-186.196 | < 6.8.0-136.136
- linux-allwinner-5.19All versions (No fix recorded)
- linux-awsAll versions (No fix recorded) | < 5.15.0-1112.119 | < 6.8.0-1061.64
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Chainguard5 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-vmware-6.18< 6.18.31-r0
Linux2 products
- linux≥ 2ecba2d1e45b24620a7c3df9531895cf68d5dec6, < 0410c619e86551677fb79887a38eccad3f5a0725 | ≥ 2ecba2d1e45b24620a7c3df9531895cf68d5dec6, < 886469b6455611a511aa6013e957e15e50577513 | ≥ 2ecba2d1e45b24620a7c3df9531895cf68d5dec6, < 46c07ad50fa2f4ba7663ee1b72b75ad7ad45cf09 | ≥ 2ecba2d1e45b24620a7c3df9531895cf68d5dec6, < eb3765b90eb8f2a3d6310a80c14a9e57ec4267a2 | ≥ 2ecba2d1e45b24620a7c3df9531895cf68d5dec6, < a69738efea0996d05a3c7d2178551b891744df1b | ≥ 2ecba2d1e45b24620a7c3df9531895cf68d5dec6, < ec4930979b3f7bbeb7af5744599fc6603a4dba62 | ≥ 2ecba2d1e45b24620a7c3df9531895cf68d5dec6, < 3d165d975305cf76ff0b10a3c798fb31e5f5f9a5 | ≥ 2ecba2d1e45b24620a7c3df9531895cf68d5dec6, < c842743d073bdd683606cb414eb0ca84465dd834 | 3764bfae5056e95617b6ee074129297e11710886 | ≥ 4.19.99, < 4.20 | 5.1
- linux_kernel≥ 4.19.99, < 4.20 | ≥ 5.1, < 6.6.136 | ≥ 6.7, < 6.12.83 | ≥ 6.13, < 6.18.24 | ≥ 6.19, < 6.19.14 | 7.0:rc1 | 7.0:rc2 | 7.0:rc3 | 7.0:rc4 | 7.0:rc5 | 7.0:rc6 | 7.0:rc7
Debian1 product
- linux< 6.1.176-1 | < 6.12.85-1 | < 6.19.14-1
4 vendors · 161 products
