CVE-2026-63994
Medium
Elevated severity or exploit probability.
CVSS base
9.8
CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS — probability of exploitation (30 days)
0.8%
53.2th percentile
CISA KEV
Not listed
Weakness / dates
—
Published 2026-07-19 · modified 2026-07-30
Description
In the Linux kernel, the following vulnerability has been resolved: tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]() Sashiko found that iptunnel_pmtud_build_icmp() and iptunnel_pmtud_build_icmpv6() were caching ip_hdr() and ipv6_hdr() before an skb_cow() call which can reallocate skb->head. Fix this possible UAF by initializing the local variables after the skb_cow() call. Remove skb_reset_network_header() calls which were not needed.
References
- https://git.kernel.org/stable/c/50750d86a2e5266aba0c295483b3397843198b11
- https://git.kernel.org/stable/c/6dff77899b9e9fe5d854abda3a98ad04e7229ef7
- https://git.kernel.org/stable/c/7254aef4d1a7e18e887af9010e2f2dc34806789b
- https://git.kernel.org/stable/c/76cd9398a0470257ab765bdf5f358a2af2e17934
- https://git.kernel.org/stable/c/95b6d772bfe788331d9742d73eaa12e113b2adc4
- https://git.kernel.org/stable/c/b4bc94353050b1fa7b702bd4c6600710dd926cff
- https://git.kernel.org/stable/c/bf8b3f34c37c162357138e7c0942723b8b94fed1
- https://git.kernel.org/stable/c/f3f204541f280a6ecb04503a0d6794d93990ca43