CVE-2026-120033 Denial of service in frrouting
A BGP neighbor can crash FRRouting bgpd or leave sessions stuck, disrupting all BGP sessions on the router.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Harmful if only installed
- No
- Needs a specific call
- No
- Fix
- None listed
What is CVE-2026-120033?
CVE-2026-120033 is a medium-severity denial of service vulnerability in frrouting, published on 12 Nov 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2026-120033?
An affected version is exposed as installed. No special setting or call is needed.
How do I fix CVE-2026-120033?
No fix has been published for CVE-2026-120033 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-120033 being exploited?
There is no known exploitation of CVE-2026-120033 in the wild and no public exploit code.
Sources
Also known as GHSA-hgqg-fv3w-2x5g.