The vulnerability CVE-2026-37457 exists in the bgp_flowspec_op_decode() function within the bgpd/bgp_flowspec_util.c source file of FRRouting stable/10.0. It is an off-by-one out-of-bounds write that can be triggered by an attacker providing a specially crafted FlowSpec component. This results in a denial of service condition. Red Hat's security advisories confirm the issue and provide updated FRRouting packages (version 10.4.4-1.el10_2 and later) that fix this vulnerability. The advisories cover multiple architectures and variants of Red Hat Enterprise Linux 10.

Successful exploitation of this vulnerability allows an unauthenticated remote attacker to cause a denial of service by crashing the FRRouting daemon handling BGP FlowSpec components. There is no indication of confidentiality or integrity impact. The CVSS 3.1 vector indicates network attack vector, low attack complexity, no privileges required, no user interaction, and impact limited to availability (DoS). No known exploits in the wild have been reported as of the advisory date.

Red Hat has released security updates for FRRouting that address this vulnerability. Users of Red Hat Enterprise Linux 10 and its variants should apply the updated FRRouting packages (e.g., frr-10.4.4-1.el10_2) as provided in the Red Hat advisories RHSA-2026:24347 and related errata. Detailed update instructions are available at https://access.redhat.com/articles/11258. Applying these official patches fully mitigates the vulnerability. No additional mitigations are specified or required beyond applying the vendor-provided updates.