CVE-2026-63992
Linux Kernel out-of-bounds read
- Published19 Jul 2026
Description
In the Linux kernel, the following vulnerability has been resolved: tunnels: do not assume transport header in iptunnel_pmtud_check_icmp() In some cases, iptunnel_pmtud_check_icmp() can be called while skb transport header is not set. This triggers an out-of-bound access, because (typeof(skb->transport_header))~0U is 65535. Access the icmp header based on IPv4 network header, after making sure icmp->type is present in skb linear part. Note that iptunnel_pmtud_check_icmpv6()) is fine.
CVSS 3.1 breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:HAffected products
Remediation
- 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
References
- 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
Related CVEs
Recent high-severity vulnerabilities sharing a weakness type.
Frequently asked
Is CVE-2026-63992 being actively exploited?
CVE-2026-63992 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.51%.
How severe is CVE-2026-63992?
CVE-2026-63992 has a CVSS 3.1 base score of 9.1, rated critical. EPSS estimates a 0.51% probability of exploitation.
Which products are affected by CVE-2026-63992?
Affected products include Linux Kernel.
How do I fix CVE-2026-63992?
Upgrade affected software to a fixed version, for example Linux Kernel 5.15.210 or later, then confirm no affected versions remain in your inventory.
How Secuno handles this
Secuno correlates vulnerabilities like CVE-2026-63992 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.
Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.