Linux Kernel up to 6.19.12 GRP_ACK_MSG tipc_group_proto_rcv privilege escalation

CVSS Meta Temp Score
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CTI Interest Score
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5.3$0-$5k0.00

Summaryinfo

A vulnerability has been found in Linux Kernel up to 6.19.12 and classified as critical. This impacts the function tipc_group_proto_rcv of the component GRP_ACK_MSG Handler. This manipulation causes an unknown weakness. This vulnerability is tracked as CVE-2026-31662. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.19.12. It has been declared as critical. Affected by this vulnerability is the function tipc_group_proto_rcv of the component GRP_ACK_MSG Handler. The impact remains unknown. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: tipc: fix bc_ackers underflow on duplicate GRP_ACK_MSG The GRP_ACK_MSG handler in tipc_group_proto_rcv() currently decrements bc_ackers on every inbound group ACK, even when the same member has already acknowledged the current broadcast round. Because bc_ackers is a u16, a duplicate ACK received after the last legitimate ACK wraps the counter to 65535. Once wrapped, tipc_group_bc_cong() keeps reporting congestion and later group broadcasts on the affected socket stay blocked until the group is recreated. Fix this by ignoring duplicate or stale ACKs before touching bc_acked or bc_ackers. This makes repeated GRP_ACK_MSG handling idempotent and prevents the underflow path.

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2026-31662 since 03/09/2026. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/03/2026).

The vulnerability scanner Nessus provides a plugin with the ID 324048 (SUSE SLED15: cluster-md-kmp-default / dlm-kmp-default / gfs2-kmp-default / etc (SUSE-SU-2026:2238-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.10.253, 5.15.203, 6.1.169, 6.6.135, 6.12.82, 6.18.23 or 6.19.13 eliminates this vulnerability. Applying the patch a7db57ccca21f5801609065473c89a38229ecb92/36ec4fdd6250dcd5e73eb09ea92ed92e9cc28412/575faea557f1a184a5f09661bd47ebd3ef3769f8/3bcf7aca63f0bcd679ae28e9b99823c608e59ce3/a2ea1ef0167d7a84730638d05c20ccdc421b14b6/1b6f13f626665cac67ba5a012765427680518711/e0bb732eaf77f9ac2f2638bdac9e39b81e0a9682/48a5fe38772b6f039522469ee6131a67838221a8 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 vulnerability database at Tenable (324048). Statistical analysis made it clear that VulDB provides the best quality 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: 5.3

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

CVSSv2info

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

Exploitinginfo

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

Physical: No
Local: No
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 324048
Nessus Name: SUSE SLED15: cluster-md-kmp-default / dlm-kmp-default / gfs2-kmp-default / etc (SUSE-SU-2026:2238-1)

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.10.253/5.15.203/6.1.169/6.6.135/6.12.82/6.18.23/6.19.13
Patch: a7db57ccca21f5801609065473c89a38229ecb92/36ec4fdd6250dcd5e73eb09ea92ed92e9cc28412/575faea557f1a184a5f09661bd47ebd3ef3769f8/3bcf7aca63f0bcd679ae28e9b99823c608e59ce3/a2ea1ef0167d7a84730638d05c20ccdc421b14b6/1b6f13f626665cac67ba5a012765427680518711/e0bb732eaf77f9ac2f2638bdac9e39b81e0a9682/48a5fe38772b6f039522469ee6131a67838221a8

Timelineinfo

03/09/2026 CVE reserved
04/24/2026 +45 days Advisory disclosed
04/24/2026 +0 days VulDB entry created
07/03/2026 +70 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-31662 (🔒)
GCVE (CVE): GCVE-0-2026-31662
GCVE (VulDB): GCVE-100-359467

Entryinfo

Created: 04/24/2026 18:59
Updated: 07/03/2026 19:58
Changes: 04/24/2026 18:59 (58), 07/03/2026 19:58 (2)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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