PT-2026-61311 · Linux · Linux Kernel

CVE-2026-63994 · Published 2026-07-19 · Updated 2026-07-19

Positive Technologies (AI Summary)

CVSS v3.1

9.8

Critical

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Name of the Vulnerable Software and Affected Versions Linux kernel (affected versions not specified)

Description A Use-After-Free (UAF) issue exists in the tunnels module. The functions iptunnel pmtud build icmp() and iptunnel pmtud build icmpv6() cache ip hdr() and ipv6 hdr() before calling skb cow(). Because skb cow() can reallocate skb->head, the cached headers may point to memory that has been freed.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Related Identifiers

CVE-2026-63994

Affected Products

Linux Kernel

References · 11

• https://nvd.nist.gov/vuln/detail/CVE-2026-63994 · Security Note
• https://git.kernel.org/stable/c/f3f204541f280a6ecb04503a0d6794d93990ca43 · Note
• https://git.kernel.org/stable/c/b4bc94353050b1fa7b702bd4c6600710dd926cff · Note
• https://git.kernel.org/stable/c/6dff77899b9e9fe5d854abda3a98ad04e7229ef7 · Note
• https://git.kernel.org/stable/c/7254aef4d1a7e18e887af9010e2f2dc34806789b · Note
• https://twitter.com/infoflowcloud/status/2078862732300870106 · Twitter Post
• https://twitter.com/CVEnew/status/2078861455605092544 · Twitter Post
• https://git.kernel.org/stable/c/50750d86a2e5266aba0c295483b3397843198b11 · Note
• https://git.kernel.org/stable/c/bf8b3f34c37c162357138e7c0942723b8b94fed1 · Note
• https://git.kernel.org/stable/c/95b6d772bfe788331d9742d73eaa12e113b2adc4 · Note
• https://git.kernel.org/stable/c/76cd9398a0470257ab765bdf5f358a2af2e17934 · Note