Out-of-bounds read in Linux kernel - CVE-2026-63992
Published: July 20, 2026
Vulnerability identifier: #VU138656
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-63992
CWE-ID: CWE-125
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Linux Foundation
Affected software:
Linux kernel
Linux kernel
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to an out-of-bounds read in iptunnel_pmtud_check_icmp() when processing ICMP packets without a valid transport header. A remote attacker can send a specially crafted packet to cause a denial of service.
The issue occurs because the function may be called while the skb transport header is not set.
How to mitigate CVE-2026-63992
Install security update from vendor's repository.
Sources
- https://git.kernel.org/stable/c/43368636c663cff6e59dde93cf4b8e43ac28eb93
- https://git.kernel.org/stable/c/509323077ef79a26ba0c60bb556e45c12c398b2d
- https://git.kernel.org/stable/c/5a92cb45e34749865d03daf8d3500f77b5f6644c
- https://git.kernel.org/stable/c/7f4f7efe7f30edd29c4988de01728bf2398217e4
- https://git.kernel.org/stable/c/a096b6e34f602950af9a2b0856cd93a5f4c276d7
- https://git.kernel.org/stable/c/c7b7ec3e69e673c0d6b57f74d21da50c485c598e
- https://git.kernel.org/stable/c/cb549df9ce4ee15c9d5b19ddab12cf2128e4313c
- https://git.kernel.org/stable/c/e917d0c69f01af2bb4fbea2b66d560a53b3ac7ec