FRRouting bgpd resource consumption

Summaryinfo

A vulnerability was found in FRRouting. It has been classified as critical. This vulnerability affects unknown code of the component bgpd. This manipulation causes resource consumption. This vulnerability appears as CVE-2026-120033. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability classified as critical was found in FRRouting (unknown version). Affected by this vulnerability is an unknown code block of the component bgpd. The manipulation with an unknown input leads to a resource consumption vulnerability. The CWE definition for the vulnerability is CWE-400. The product does not properly control the allocation and maintenance of a limited resource. As an impact it is known to affect availability. The summary by CVE is:

In FRRouting 10.1 and later, bgpd does not correctly close a BGP session when the Send Hold Timer (RFC 9687) expires, i.e. when a neighbor has stopped accepting data from the router for twice the hold time. The connection is closed, but bgpd still considers the session to be up. A BGP neighbor that keeps sending KEEPALIVEs but stops reading from its connection, at a time when the router has a large amount of data to send to it (for example while sending it a full routing table), can cause one of the following: * If the neighbor announced Graceful Restart support: bgpd crashes shortly after the session is closed (after the neighbor's announced restart time plus one keepalive interval), taking down all BGP sessions on the router. The neighbor can repeat this each time bgpd restarts. * Otherwise: the session stays stuck in the Established state. The neighbor's routes stay installed and keep being advertised to other peers, and the neighbor cannot reconnect until an operator runs "clear bgp <neighbor>". The neighbor does not need to be malicious; an overloaded or stuck peer can trigger the same behavior. Required configuration: no special configuration is needed. Any BGP neighbor with an established session can trigger the issue under default settings, for example: router bgp 65001 neighbor 192.0.2.2 remote-as 65002 Graceful Restart helper mode, which leads to the crash, is enabled by default. With default timers (keepalive 60s, hold time 180s), the session is closed about 6 minutes after the neighbor stops reading.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-120033 since 10/30/2026. The exploitation appears to be easy. The attack can be launched remotely. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Name

• FRRouting

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CPE 2.2info

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