Out-of-bounds read in Linux kernel - CVE-2026-63920
Published: July 20, 2026
Vulnerability identifier: #VU138725
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-63920
CWE-ID: CWE-125
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vendor: Linux Foundation
Affected software:
Linux kernel
Linux kernel
Detailed vulnerability description
The vulnerability allows a local user to disclose sensitive information.
The vulnerability exists due to an out-of-bounds read in ip6_datagram_recv_specific_ctl() when processing IPv6 extension headers for recvmsg control messages after the hdrlen field is modified. A local user can use an nftables payload-write expression to corrupt the extension header length and trigger copying beyond the available header data to disclose sensitive information.
Exploitation is reachable from an unprivileged user namespace.
How to mitigate CVE-2026-63920
Install security update from vendor's repository.
Sources
- https://git.kernel.org/stable/c/08464413e628803bd10cb1df68d0138665f2f885
- https://git.kernel.org/stable/c/0d330eff318c0f44d4fb0ad2c2aef38f87f24c90
- https://git.kernel.org/stable/c/81394827dfb72772c50d0ae3bdfa094428a5d76d
- https://git.kernel.org/stable/c/931b4a1f13408c2507719890f78f7227c34a0282
- https://git.kernel.org/stable/c/a29768d56eb3798c052ad3281b05596e695a17af
- https://git.kernel.org/stable/c/a35daeabb433686234b010ebf7b53778dbd6c9b8
- https://git.kernel.org/stable/c/dd433671fef381fdaf7b530c631e6b782d66e224
- https://git.kernel.org/stable/c/eb18a1b1644e4cad978df2131e2bb9a2e6886992