October 7, 2026

CVE Watchtower

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CVE-2026-63994NVD

Vulnerability Summary

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.
Severity Level
CRITICAL(9.8)
Published Date
Jul 19, 2026
Last Modified
Oct 7, 2026
Exploitation Status
No confirmed exploitation yet
EPSS Score (30-Day)
0.51%Probability
Root Weakness (CWE)
CWE-416: Unknown/Unlisted Weakness ↗
Refer to the official MITRE database for detailed architectural specifications regarding this weakness.
CVSS v3.1 Base Metrics — Score 9.8 (CRITICAL)
Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh

Affected & Patched Versions

Affected Versions
  • Linux Linux Kernel >= 5.9 and < 5.10.259
  • Linux Linux Kernel >= 5.11 and < 5.15.210
  • Linux Linux Kernel >= 5.16 and < 6.1.176
  • Linux Linux Kernel >= 6.2 and < 6.6.143
  • Linux Linux Kernel >= 6.7 and < 6.12.93
  • Linux Linux Kernel >= 6.13 and < 6.18.35
  • Linux Linux Kernel >= 6.19 and < 7.0.12
  • Linux Linux Kernel
Patched Versions
  • Linux Linux Kernel 5.10.259
  • Linux Linux Kernel 5.15.210
  • Linux Linux Kernel 6.1.176
  • Linux Linux Kernel 6.6.143
  • Linux Linux Kernel 6.12.93
  • Linux Linux Kernel 6.18.35
  • Linux Linux Kernel 7.0.12
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🎁7-Day Free Trial — Try Pro or Team, no card required.
📧Email Delivery — Threat intel straight to your inbox.
♾️Unlimited Vendors — Track your entire stack.
🚨All New CVEs — Be the first to know.
📈EPSS Spike Alerts — Catch rising risk before it peaks.
🎯Custom EPSS/CVSS — Filter noise, focus on risk.
🛡️Exploit Intel — A 2nd confirmed-exploit signal beyond KEV.
🐙GitHub Issues — Auto-tracked, no duplicates.
📬Weekly Digest — One clean summary, not inbox spam.
🏷️Watchlist Groups — Tag alerts by team (Infra/AppSec/SOC).
💬Webhooks — Slack & Teams integration.
🔀Smart Routing — Critical alerts to one channel, rest to another.
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External References