CVSS 4.0
6.0 mediumCVSS: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:ACVE-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) in frrouting frrouting. EPSS 0.3% estimated probability of exploitation activity in the next 30 days.
On this page
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 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.
Severity
- EPSS
- 0.3% estimated probability of exploitation activity in the next 30 days; 22nd percentile. Scored 2026-11-13. A forecast for this CVE across the internet, not for your own systems.
- Published
- Modified
- Assigned by
- NetDEF (CNA)
- NVD analysis
- Awaiting analysis
- Record from
- the NVD, synced
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Affected
Linux distributions
| Distribution | Release | Package | Fixed in | Advisory |
|---|---|---|---|---|
| Ubuntu | 20.04:LTS, Pro:16.04:LTS, Pro:18.04:LTS | quagga | no fix listed | UBUNTU-CVE-2026-120033 |
| Ubuntu | 22.04:LTS, 24.04:LTS, 26.04:LTS and 2 more | frr | no fix listed | UBUNTU-CVE-2026-120033 |
From the distributions' data via OSV.dev: Ubuntu Security Notices © Canonical Ltd., CC BY-SA 4.0. Modified: reformatted and linked to CVE records. Credits. On the distributions' own pages: Ubuntu.
Attack patterns (CAPEC)
- CAPEC-74 Manipulating State Likelihood: Medium · Severity: High
- CAPEC-140 Bypassing of Intermediate Forms in Multiple-Form Sets Severity: Medium
The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.