headroom bug

About this tag
The headroom bug tag covers a specific Linux kernel vulnerability (CVE-2025-40173) in the IPv6 tunnel code (net/ip6_tunnel) that causes perpetual tunnel headroom growth. This defect can lead to stability issues over time as headroom increases without bound. The fix involves backporting a targeted patch that imposes an upper limit on headroom adjustments, similar to an earlier IPv4 tunnel fix. While this is a Linux kernel issue, it is relevant to Windows users running virtual machines, containers, or hybrid environments that rely on IPv6 tunneling. The tag includes discussions of the bug's technical details, the patch, and distribution backports.

  1. Linux Kernel CVE-2025-40173 IPv6 Tunnel Headroom Fix and Backport

    The Linux kernel received a targeted fix for CVE-2025-40173 — a net/ip6_tunnel defect that could cause perpetual tunnel headroom growth in IPv6 tunnel code, and maintainers and distributions are already mapping and shipping backports to close the lifetime and stability gap. Background / Overview...
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    • backporting headroom bug ipv6 tunneling linux kernel
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    • Forum: Security Alerts