CVE-2026-120033: frr: bgpd Send Hold Timer expiry bypasses the FSM, leaving a phantom Established session or crashing bgpd with Graceful Restart

Is it exploited?

Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of 10 Nov 2026. If CISA adds it, this page shows it as known exploited.

How likely is exploitation in the next 30 days?

Not yet scored. FIRST's EPSS model has no score for this record as of 12 Nov 2026.

How severe?

6.0 Medium

CVSS v4.0 base score, given by the CNA

What should I do?

CISA has set no required action, because the vulnerability is not in KEV.

Advisories and patches (1)

Which versions are affected?

Affected

• 4967bf6d729d

Unaffected from 57a7f3eb4883

Versions by product

Source: CISA KEV 2026.11.10, as of 10 Nov 2026; FIRST EPSS, as of 12 Nov 2026; CVE List, as of 13 Nov 2026. About the data.

Description

frr: bgpd Send Hold Timer expiry bypasses the FSM, leaving a phantom Established session or crashing bgpd with Graceful Restart

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.

Source: CVE List, as of 13 Nov 2026. About the data.

What to do

Advisories and patches

• github.com (Patch)

Workaround (from the CVE record)

No configuration workaround fully prevents the issue. Monitor bgpd logs for "has not made any SendQ progress for 2 holdtimes" and run "clear bgp <neighbor>" for the affected neighbor, which raises a real FSM event and recovers the peer (this does not prevent the abort when Graceful Restart was negotiated, if the restart timer fires first).

This summary is based on the CVE record as of 13 Nov 2026. Check the vendor's advisory before you act: affected versions and fixes can change.

Affected products and versions

Source: CVE List, as of 13 Nov 2026. About the data.

Timeline