High [CVE-2026-63992] do not assume transport header in iptunnel_pmtud_check_icmp
This high-severity Red Hat Linux advisory covers CVE-2026-63992 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9.
Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.
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Summary
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.
An attacker could exploit this condition to trigger an out-of-bound memory access, which may lead to system instability or a denial of service. Red Hat severity: Moderate — CVSS 7 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H).
Weakness: CWE-805. Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9; Shadow Migration Toolkit for Virtualization for RHEL 10; Red Hat Enterprise Linux 6.
Red Hat lists Red Hat Enterprise Linux 7 as not affected. Will not fix / out of support: Red Hat Enterprise Linux 6.
Red Hat fixing advisory: RHSA-2026:76738, RHSA-2026:75746, RHSA-2026:75747, RHSA-2026:76739.
Affected products named by the advisory: Red Hat package: kernel-rt.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative. Check it before change work.
Official advisory · high-confidence parse· fetched 7 days ago·verify at source
- kernel-0:6.12.0-211.63.1.el10_2
- kernel-rt-0:4.18.0-553.171.1.rt7.512.el8_10
- kernel-0:4.18.0-553.171.1.el8_10
- kernel-0:5.14.0-687.55.1.el9_8
- RHSA-2026:76738
- RHSA-2026:75746
- RHSA-2026:75747
- RHSA-2026:76739
Official advisory · high-confidence parse· fetched 7 days ago·verify at source
Mitigation
Upgrade to a fixed release: kernel-0:6.12.0-211.63.1.el10_2, kernel-rt-0:4.18.0-553.171.1.rt7.512.el8_10, kernel-0:4.18.0-553.171.1.el8_10, kernel-0:5.14.0-687.55.1.el9_8, RHSA-2026:76738, RHSA-2026:75746. That is the remediation for this advisory.
The vendor advisory may list interim mitigations or workarounds not captured here. Review it before change work.
Official advisory · high-confidence parse· fetched 7 days ago·verify at source
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