TCP Use-After-Free: CVE-2026-98432 / CVSS 9.8
Article URL: https://atlasum.net/blog/cve-2026-98432-linux-ipv4-tcp-uaf Comments URL: https://news.ycombinator.com/item?id=50319143 Points: 221 # Comments: 104
A critical use-after-free vulnerability, CVE-2026-98432, affects Linux TCP handshakes. This flaw allows a remote, unauthenticated adversary to overflow kernel memory, potentially leading to system crashes or unauthorized command execution. The vulnerability, present since Linux 4.4, has been fixed in various kernel versions ranging from 5.10.272 to 7.3.
However, many servers still run outdated distributions that have not applied the fix. Ubuntu users, for instance, are still flagged as vulnerable despite a fix being available. The bug's severity is underscored by Anthropic's demonstration of a proof-of-concept exploit that could run commands as root on affected systems. The fix involves a four-line change to the kernel, which prevents the premature freeing of TCP options before the handshake is complete.
Distributions like Red Hat have elevated the severity of the bug to Critical (9.8) due to the minimal prerequisites required for exploitation and the potential for severe system instability. Immediate updates and reboots are recommended to mitigate the risk.
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Also reported by 1 other outlet
- TCP Use-After-Free: CVE-2026-98432 / CVSS 9.8 atlasum.net
