Linux Kernel up to 6.12.82/6.18.23/6.19.13 net tcf_csum_act privilege escalation

CVSS Meta Temp Score
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CTI Interest Score
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5.4$0-$5k0.00

Summaryinfo

A vulnerability described as critical has been identified in Linux Kernel up to 6.12.82/6.18.23/6.19.13. This impacts the function tcf_csum_act of the component net. Such manipulation leads to an unknown weakness. This vulnerability is listed as CVE-2026-31684. There is no available exploit. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 6.12.82/6.18.23/6.19.13. Affected by this issue is the function tcf_csum_act of the component net. The impact remains unknown. CVE summarizes:

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.

The advisory is shared for download at git.kernel.org. This vulnerability is handled as CVE-2026-31684 since 03/09/2026. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 06/04/2026).

The vulnerability scanner Nessus provides a plugin with the ID 310346 (Linux Distros Unpatched Vulnerability : CVE-2026-31684), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.12.83, 6.18.24 or 6.19.14 eliminates this vulnerability. Applying the patch a69738efea0996d05a3c7d2178551b891744df1b/ec4930979b3f7bbeb7af5744599fc6603a4dba62/3d165d975305cf76ff0b10a3c798fb31e5f5f9a5/c842743d073bdd683606cb414eb0ca84465dd834 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (310346) and EUVD (EUVD-2026-25651). Once again VulDB remains the best source for vulnerability data.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.5
VulDB Meta Temp Score: 5.4

VulDB Base Score: 5.5
VulDB Temp Score: 5.3
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 5.5
NVD Vector: 🔒

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Privilege escalation
CWE: Unknown
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 310346
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-31684

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.12.83/6.18.24/6.19.14
Patch: a69738efea0996d05a3c7d2178551b891744df1b/ec4930979b3f7bbeb7af5744599fc6603a4dba62/3d165d975305cf76ff0b10a3c798fb31e5f5f9a5/c842743d073bdd683606cb414eb0ca84465dd834

Timelineinfo

03/09/2026 CVE reserved
04/25/2026 +46 days Advisory disclosed
04/25/2026 +0 days VulDB entry created
06/04/2026 +40 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-31684 (🔒)
GCVE (CVE): GCVE-0-2026-31684
GCVE (VulDB): GCVE-100-359588
EUVD: 🔒

Entryinfo

Created: 04/25/2026 11:35
Updated: 06/04/2026 05:06
Changes: 04/25/2026 11:35 (58), 04/25/2026 13:02 (1), 04/26/2026 05:51 (2), 06/04/2026 05:06 (10)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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