What is CVE-2026-80634?

CVE-2026-80634 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.8 out of 10, affecting Linux kernel versions from 5.13 onward and patched in 7.1.5 and 7.2. CVE-2026-80634 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-80634?

CVE-2026-80634 has a CVSS score of 9.8 out of 10, rated Critical severity. The vector string is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Is there a patch available for CVE-2026-80634?

Yes, CVE-2026-80634 has been patched. Fixed versions include 7.1.5 and 7.2. If you are running Linux kernel 5.13 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-80634 actively exploited?

CVE-2026-80634 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2026-80634

Critical

In the Linux kernel, the following vulnerability has been resolved: netfilter: flowtable: avoid num_encaps underflow on bridge VLAN untag The DEV_PATH_BR_VLAN_UNTAG case post-decrements info->num_encaps inside WARN_ON_ONCE(). num_encaps is u8, so if it's already 0 the decrement still happens and wraps it to 255. The break only leaves the inner switch -- a later path entry can set info->indev back to a real device, and we end up returning with num_encaps == 255. nft_dev_forward_path() then walks info.encap[] (size 2) up to num_encaps, which means an OOB stack read and a bogus count copied into the route descriptor. Should only happen on a malformed bridge path stack, hence the WARN, but worth handling sanely. Move the decrement out of the WARN. [ While at this, remove the WARN_ON_ONCE since this can only happen with a buggy bridge path stack --pablo ].

Package Linux Kernel

Published 2026-08-28

Last modified 2026-08-29

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

9.8

out of 10

Critical

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Vector string

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected versions

Linux kernel versions 5.13 and later are affected. Fixed in 7.1.5, 7.2 and their respective stable series.

Affected from

≥ 5.13

Fixed in

✓ 7.1.5 7.1.x ✓ 7.2

References

2 total

Details

CVE ID CVE-2026-80634

Severity Critical

CVSS score 9.8 / 10

CVSS version 3.1

Published 2026-08-28

Modified 2026-08-29

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2026-80634?

CVE-2026-80634 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.8 out of 10 . It affects Linux kernel versions from 5.13 onward and has been patched in 7.1.5 and 7.2. CVE-2026-80634 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-80634?

CVE-2026-80634 has a CVSS score of 9.8 out of 10, rated Critical severity (CVSS 3.1). The vector string is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
Is there a patch available for CVE-2026-80634?

Yes. CVE-2026-80634 has been patched. Fixed versions include 7.1.5 and 7.2. If you are running Linux kernel 5.13 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-80634 actively exploited?

No. CVE-2026-80634 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.