CVE
FRRouting remote denial of service in bgpd via double free
- Exploited
- No known exploitation
- Fix
- Fix or patch referenced
- Who is exposed
- Not reported
Do first: Apply the patch listed under Evidence.
- Published
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 25/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Unclear
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
FRRouting's bgpd daemon, the BGP routing component, can be crashed remotely, without logging in, by any host whose address falls inside a configured "bgp listen range" when that peer-group also has a Site-of-Origin set. Opening and closing two TCP connections to the BGP port makes bgpd free the same memory twice, which aborts the daemon and drops all BGP sessions on the router.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original description
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.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure17/25No login or user action needed, reachable over the network without a login · Unknown: Advisories don't say whether default setups are affected
- Reach?/20Unknown. No tracked technology or package matched
- Severity8.2/10CVSS 8.2
- No patch0/5No signal
What would change the score
- Would score about 70 if added to CISA KEV
- Would score about 65 if CISA's SSVC rates exploitation active
- Would score about 30 if advisories confirm default setups are exposed
What to do
Apply the patch listed under Evidence.
Workaround: Do not configure "neighbor <peer-group> soo" on a peer-group used by "bgp listen range".
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
Check whether my systems are affected by CVE-2026-120221 (frr: bgpd double free of peer-group Site-of-Origin when dynamic neighbors disconnect), using the cve.now data below.
Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.
What cve.now has for CVE-2026-120221 (entry last updated 2026-11-13):
Affected:
- frrouting frrouting: version range not reported
Fixed versions: none listed yet.
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
Attacker needs: network access, no login, no user action.
Workaround: Do not configure "neighbor <peer-group> soo" on a peer-group used by "bgp listen range". (source: https://www.cve.org/CVERecord?id=CVE-2026-120221)
CISA KEV: CVE-2026-120221 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-120221 only. If you also check another CVE, look up its own KEV status; never assume it from this one.
How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.
Verify against the linked advisories before concluding, and cite the date you read each one:
- https://github.com/FRRouting/frr/pull/21685/changes/6a96f515760dc278147fbf802777956ba80c7edd
- https://www.cve.org/CVERecord?id=CVE-2026-120221
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.
Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.
Entry: https://cve.now/CVE-2026-120221
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-120221"}.Timeline
- CVE published
- First seen by cve.now
Affected versions
- frrouting frrouting
Version range not reported
Evidence 3
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Other links · 1
- Patch
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-120221
Is CVE-2026-120221 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
How do I fix CVE-2026-120221?
No fixed version or patch is listed in the checked facts. Avoid configuring "neighbor <peer-group> soo" on a peer-group used by "bgp listen range".Source: cve.org