CVE-2026-118593

A flaw was found in Red Hat Enterprise Linux 9 kernel builds. An incomplete backport of the CVE-2026-46099 fix in RHEL 9.6 through 9.10 left a local_bh imbalance in seg6_input_core(), where the drop path returns with bottom halves still disabled. This can lead to softirq starvation and denial of service on systems with SRv6 tunnels configured. Upstream and RHEL 10 are not affected.

This vulnerability is rated as Moderate severity because exploitation requires an atypical network setup using Segment Routing over IPv6 (SRv6) lightweight tunnels and can only lead to a denial of service. Under default configurations, SRv6 tunneling is not active, limiting the attack surface to specialized routing deployments. If an affected host routes specially crafted packets that trigger a routing lookup failure in the tunnel subsystem, bottom halves remain disabled, potentially resulting in system hangs without compromising confidentiality or integrity.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.