CVE-2026-120033

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

Medium 6.0

Description

In FRRouting, 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 trigger this. If the neighbor announced Graceful Restart support, bgpd crashes shortly after the session is closed, taking down all BGP sessions on the router, and 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 clears the session manually. The neighbor does not need to be malicious; an overloaded or stuck peer can trigger the same behavior. No special configuration is required: any established BGP neighbor can trigger the issue, and Graceful Restart helper mode, which leads to the crash, is enabled by default.

Key facts

Published: 12 Nov 2026
Last changed: 14 Nov 2026
Assigned by: NetDEF
EPSS: 0.294% likely to be exploited in the next 30 days, higher than 22.237% of CVEs (scores for 15 Nov 2026)

Severity scores

Each score is shown as its source gave it. They are not averaged or merged.

6.0CVSS 4.0, Mediumfrom the CNA (NetDEF)CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:H/SC:N/SI:L/SA:L/AU:N/R:A

What to do

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).CNA workaround statement

Historical context and remediation

This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.

No separately sourced impact summary is available on this page yet. Consult the description, version data and dated exploitation evidence.

Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.

Read the original CVE record.

Affected products

Vendor	Product	Versions
frrouting	frrouting	Default status: unaffected 4967bf6d729d7dd14dff7b672b2fd4afe78a0d86 up to but excluding * (affected); at 57a7f3eb48837359d6e3ee5ebd4acea8f49320e5 unaffected 10.1.0 up to but excluding 10.4.6 (affected) 10.5.0 up to but excluding 10.5.6 (affected) 10.6.0 up to but excluding 10.6.3 (affected) 10.7.0 up to but excluding 10.7.2 (affected)