Description
In the Linux kernel, the following vulnerability has been resolved:

xfrm: ah6: validate routing header segments_left

AH6 rearranges routing-header addresses before computing or verifying the
ICV. ipv6_rearrange_rthdr() assumes that segments_left is not larger than
the number of addresses described by the routing header's hdrlen field.

That assumption does not hold for raw IPv6 HDRINCL packets. A packet with
hdrlen equal to 2 describes one address, but can carry an arbitrary
segments_left value. With segments_left equal to 255, the function moves
its address pointer 4,064 bytes backwards and passes a 4,064-byte length to
memmove(), resulting in an out-of-bounds access.

Validate the invariant locally before modifying the routing header or
performing any address-pointer arithmetic, and propagate malformed-header
errors to the existing AH6 input and output error paths.
Published: 2026-09-04
Score: n/a
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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Remediation

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History

Fri, 04 Sep 2026 16:00:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: xfrm: ah6: validate routing header segments_left AH6 rearranges routing-header addresses before computing or verifying the ICV. ipv6_rearrange_rthdr() assumes that segments_left is not larger than the number of addresses described by the routing header's hdrlen field. That assumption does not hold for raw IPv6 HDRINCL packets. A packet with hdrlen equal to 2 describes one address, but can carry an arbitrary segments_left value. With segments_left equal to 255, the function moves its address pointer 4,064 bytes backwards and passes a 4,064-byte length to memmove(), resulting in an out-of-bounds access. Validate the invariant locally before modifying the routing header or performing any address-pointer arithmetic, and propagate malformed-header errors to the existing AH6 input and output error paths.
Title xfrm: ah6: validate routing header segments_left
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-09-04T15:54:54.295Z

Reserved: 2026-08-26T14:34:25.796Z

Link: CVE-2026-80844

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-04T16:18:13.023

Modified: 2026-09-04T16:18:13.023

Link: CVE-2026-80844

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses

No weakness.