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

Status: published. Published: 2026-11-12. Updated: 2026-11-12.

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.

## Remediation

- workaround: 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). (source: CNA: NetDEF)
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: NetDEF) — https://github.com/FRRouting/frr/pull/23945/changes/57a7f3eb48837359d6e3ee5ebd4acea8f49320e5

## Affected products and versions

- frrouting / frrouting: ≥ 4967bf6d729d7dd14dff7b672b2fd4afe78a0d86; < * (affected, git); unaffected at 57a7f3eb48837359d6e3ee5ebd4acea8f49320e5. Source: CNA: NetDEF

## Severity and prioritization

- CVSS 4.0: 6 (medium); 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; source: CNA: NetDEF

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-617, CWE-372

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/FRRouting/frr/pull/23945/changes/57a7f3eb48837359d6e3ee5ebd4acea8f49320e5 (CNA: NetDEF; patch)

## Provenance

- CNA: NetDEF: https://www.cve.org/CVERecord?id=CVE-2026-120033; retrieved 2026-11-12; source updated 2026-11-12

Revision: 57bf88911d3790aa768d35593d104676424ad182a65cf19adad59d637cea0d34

Canonical: https://y2.dev/cve/CVE-2026-120033

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