CVE-2026-98853

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

net: gso: limit recursive IP-in-IP segmentation

IP-in-IP GSO can re-enter inet_gso_segment() or ipv6_gso_segment()

for each nested IP header. encap_level tracks header bytes, not callback

depth, so a deep chain can exhaust the kernel stack. Making

inet_gso_segment() stackable introduced unbounded IPv4 nesting; IPIP

GSO/TSO later made the path reachable. The IPv6 stackable path was

introduced separately and uses the same guard.

Count IPv4 and IPv6 GSO handler entries in skb_gso_cb, initialized once

per top-level GSO operation and preserved across GRE/UDP context changes.

Use the existing IP_TUNNEL_RECURSION_LIMIT for both handlers. The first

five entries pass, and the sixth returns -EINVAL before dispatching

another GSO callback.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References