Out-of-bounds write in Linux kernel - CVE-2026-80840
Published: September 5, 2026
Vulnerability identifier: #VU147078
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-80840
CWE-ID: CWE-787
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause an out-of-bounds write.
The vulnerability exists due to improper initialization of the IPv4 control block in the IPv6 Segment Routing decapsulation path when processing a specially crafted IPv6 packet containing an encapsulated IPv4 TCP SYN packet. A remote attacker can send a specially crafted packet with controlled IPv6 extension-header and IPv4 option data to cause an out-of-bounds write.
Affected software
Linux kernel
How to mitigate CVE-2026-80840
Install security update from vendor's repository.
External References
- https://git.kernel.org/stable/c/0e3f01fe2e704e76af4385b8a1742641885a191c
- https://git.kernel.org/stable/c/10fd1a8f58ac619a9e251f2858e2e2c8fd6cd667
- https://git.kernel.org/stable/c/3e4476e58343fb8f2fffced9e22d935376b17aaf
- https://git.kernel.org/stable/c/44930446dde45a7a90fe1446fa38eb0e2c561646
- https://git.kernel.org/stable/c/9039e4f3e1c0ffe2b575b655b3f58fdd10f7e40c
- https://git.kernel.org/stable/c/bf1c1151560d11036a144d917fa4c131831342d7
- https://git.kernel.org/stable/c/eb0f422487228e140f3d609b032ac61aedcab8fa
- https://git.kernel.org/stable/c/f4be3b391265e24c7720fc867c50062b436acf33
- https://git.kernel.org/stable/c/f52f1e75716d2ee49e013edf204ac92337c72fd8