CVE-2026-63994tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()
- 9.8CriticalCVSS base score
- 0.51%Exploitation in 30 daysEPSS · top 56% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By Linux
Published
- 3 months later
· 3 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | Critical9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Modified | 3.1 | Critical9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.51% · top 56% of all CVEs (15 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.8.
Affected products
- affected 4cb47a8644cc9eb8ec81190a50e79e6530d0297f – < 95b6d772bfe788331d9742d73eaa12e113b2adc4
- affected 4cb47a8644cc9eb8ec81190a50e79e6530d0297f – < 7254aef4d1a7e18e887af9010e2f2dc34806789b
- affected 4cb47a8644cc9eb8ec81190a50e79e6530d0297f – < bf8b3f34c37c162357138e7c0942723b8b94fed1
- affected 4cb47a8644cc9eb8ec81190a50e79e6530d0297f – < 76cd9398a0470257ab765bdf5f358a2af2e17934
- affected 4cb47a8644cc9eb8ec81190a50e79e6530d0297f – < 50750d86a2e5266aba0c295483b3397843198b11
- affected 4cb47a8644cc9eb8ec81190a50e79e6530d0297f – < 6dff77899b9e9fe5d854abda3a98ad04e7229ef7
- affected 4cb47a8644cc9eb8ec81190a50e79e6530d0297f – < f3f204541f280a6ecb04503a0d6794d93990ca43
- affected 4cb47a8644cc9eb8ec81190a50e79e6530d0297f – < b4bc94353050b1fa7b702bd4c6600710dd926cff
- affected 5.9
- unaffected < 5.9
- unaffected 5.10.259 – ≤ 5.10.*
- unaffected 5.15.210 – ≤ 5.15.*
- unaffected 6.1.176 – ≤ 6.1.*
- unaffected 6.6.143 – ≤ 6.6.*
- unaffected 6.12.93 – ≤ 6.12.*
- unaffected 6.18.35 – ≤ 6.18.*
- unaffected 7.0.12 – ≤ 7.0.*
- unaffected 7.1 – ≤ *
References
References8
- https://git.kernel.org/stable/c/95b6d772bfe788331d9742d73eaa12e113b2adc4 (opens in a new tab)
- https://git.kernel.org/stable/c/7254aef4d1a7e18e887af9010e2f2dc34806789b (opens in a new tab)
- https://git.kernel.org/stable/c/bf8b3f34c37c162357138e7c0942723b8b94fed1 (opens in a new tab)
- https://git.kernel.org/stable/c/76cd9398a0470257ab765bdf5f358a2af2e17934 (opens in a new tab)
- https://git.kernel.org/stable/c/50750d86a2e5266aba0c295483b3397843198b11 (opens in a new tab)
- https://git.kernel.org/stable/c/6dff77899b9e9fe5d854abda3a98ad04e7229ef7 (opens in a new tab)
- https://git.kernel.org/stable/c/f3f204541f280a6ecb04503a0d6794d93990ca43 (opens in a new tab)
- https://git.kernel.org/stable/c/b4bc94353050b1fa7b702bd4c6600710dd926cff (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-45567 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
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[](https://cveledger.app/cve/CVE-2026-63994)Record last updated .