CVE-2026-120221: frr: bgpd double free of peer-group Site-of-Origin when dynamic neighbors disconnect

Is it exploited?

Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of 13 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 13 Nov 2026.

How severe?

8.2 High

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

• 01da2d26911c

Unaffected from 6a96f515760d

Versions by product

Source: CISA KEV 2026.11.13, as of 13 Nov 2026; FIRST EPSS, as of 13 Nov 2026; CVE List, as of 14 Nov 2026. About the data.

Description

frr: bgpd double free of peer-group Site-of-Origin when dynamic neighbors disconnect

In FRRouting 8.4 and later, bgpd frees the same memory twice when dynamic BGP neighbors disconnect, if the peer-group used by a "bgp listen range" also has a Site-of-Origin configured ("neighbor PG soo"). Each dynamic neighbor shares the peer-group's SoO value instead of getting its own copy, but frees it as its own when the neighbor is deleted, which happens as soon as its connection closes. The first disconnect leaves the peer-group pointing at freed memory, and the second disconnect frees it again, causing bgpd to abort and drop all BGP sessions on the router. Any host whose address falls inside the listen range can trigger this by opening and closing two TCP connections to the BGP port, without sending any BGP message and without knowing the AS number, and can repeat it each time bgpd restarts. If the peer-group has a TCP-MD5 password, only hosts that know the password can trigger it. Two ordinary flaps of legitimate dynamic neighbors have the same effect. Between the two frees, displaying the configuration ("show running-config") or establishing a dynamic neighbor also reads the freed memory, which can crash bgpd after a single disconnect. Only configurations that combine a listen range with a SoO on the same peer-group are affected.

Source: CVE List, as of 14 Nov 2026. About the data.

What to do

Advisories and patches

• github.com (Patch)

Workaround (from the CVE record)

Do not configure "neighbor <peer-group> soo" on a peer-group used by "bgp listen range". Instead, set the SoO extended community with an inbound route-map, or set "neighbor soo" on statically configured neighbors. Configuring a TCP-MD5 "password" on the peer-group limits the trigger to hosts that know the key.

This summary is based on the CVE record as of 14 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 14 Nov 2026. About the data.

Timeline