CVE-2026-80844
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.
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Exploitation outlook
- Low exploitation risk0.19% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 9% of all EPSS-scored CVEs.
Advisory coverage (2)
- mediumCVE-2026-80844: xfrm: ah6: validate routing header segments_leftmsrc · 2026-09-08
- unknownCVE-2026-80844: In the Linux kernel, the following vulnerability has been resolved: xfrm: ah6: validate routin…nvd · 2026-09-04
External references
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