High [CVE-2026-74669] clear IPv4 options after rebasing tunnel ICMP errors
This high-severity Red Hat Linux advisory covers CVE-2026-74669 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8.
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Summary
In the Linux kernel, the following vulnerability has been resolved: ipvs: clear IPv4 options after rebasing tunnel ICMP errors ip_vs_in_icmp() rebases an skb from the outer ICMP packet to the quoted original request before passing it to icmp_send(). However, IPCB(skb)->opt still describes the outer IPv4 header.
A timestamp option in the outer header can therefore leave an offset that points into the quoted transport header after the rebase. __ip_options_echo() treats a byte at that stale location as the option length and copies it into the fixed-size option storage on the __icmp_send() stack, causing a stack out-of-bounds write.
Clear the stale option metadata after resetting the network header. Keep the remaining control block fields, including the ingress interface used by the ICMP response path.
A flaw was found in the Linux kernel's IP Virtual Server (IPVS) component. When processing Internet Control Message Protocol (ICMP) errors for tunneled packets, the system can incorrectly use a stale IPv4 option offset.
A remote attacker could exploit this by sending a specially crafted ICMP packet, leading to a stack out-of-bounds write. This vulnerability could result in a denial of service or potentially arbitrary code execution.
Red Hat severity: Important — CVSS 8.8 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H). Weakness: CWE-787.
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 12 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 12 days ago·verify at source
Mitigation checklist
- To mitigate this issue, prevent the `ip_vs` kernel module from loading. This can be achieved by creating a blacklist rule. 1. Unload the module if currently loaded: `sudo modprobe -r ip_vs` 2. Create a blacklist configuration file: `echo "blacklist ip_vs" | sudo tee /etc/modprobe.d/disable-ip_vs.conf` 3. Rebuild the initial RAM disk to ensure the module is not loaded at boot: `sudo dracut -f` A system reboot is required for the changes to take full effect. Disabling this module will prevent the use of IP Virtual Server (IPVS) functionality.
Official advisory · high-confidence parse· fetched 12 days ago·verify at source
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