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FRRouting out-of-bounds read and crash in bgpd

CVE-2026-129217

CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:L/VI:H/VA:H/SC:N/SI:N/SA:N

6.0MediumCNA
Exploited
No known exploitation
Fix
Fixed in 10.5.2, 10.4.3, 10.3.4, 10.2.6, 10.1.5, and 1 more
Who is exposed
Not reported

Do first: Upgrade to a fixed version: 10.5.2, 10.4.3, 10.3.4, 10.2.6, 10.1.5, or one of 1 more.

Published
Last modified
Reference
Last checked
0.33% · 27th percentile
9/100 · provisional
None on Exploit-DB, Metasploit or GitHub

Summary

A remote BGP peer that has already established a session with FRRouting's bgpd daemon can crash it by sending a malformed NOTIFICATION Cease/Hard Reset message whose data field is exactly one byte, which triggers an out-of-bounds heap read and an assertion failure. The crash terminates all BGP sessions, causing a denial of service.

Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.

Original description

In FRRouting (FRR) 8.3 through 10.5.1, bgp_notify_decapsulate_hard_reset() in bgpd/bgp_packet.c does not validate the length of the data field of a received BGP NOTIFICATION Cease/Hard Reset message (RFC 8538). When the data field is exactly one byte long, the function reads one byte past the end of a heap buffer and the 16-bit length of the encapsulated data underflows to 65535, causing a 65535-byte out-of-bounds heap read followed by an assertion failure. A remote BGP peer that has established a session and negotiated the Graceful Restart capability with the Notification (N) bit can send such a message to crash the bgpd daemon, terminating all BGP sessions (denial of service). This is fixed in 10.0.5, 10.1.5, 10.2.6, 10.3.4, 10.4.3, 10.5.2 and 10.6.0.

cve.now Index

9Pcve.now Index 9 of 100 · methodology v3 · provisional
  • Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
  • Exposure3/25Reachable over the network · Unknown: No advisory context yet
  • Reach?/20Unknown. No tracked technology or package matched
  • Severity6/10CVSS 6.0
  • No patch0/5No signal

What would change the score

  • Would score about 64 if added to CISA KEV
  • Would score about 59 if CISA's SSVC rates exploitation active
  • Would score about 28 if advisories confirm default setups are exposed

How the score works · Rankings

What to do

  • Upgrade to a fixed version: 10.5.2, 10.4.3, 10.3.4, 10.2.6, 10.1.5, or one of 1 more.

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-2026-129217 (bgpd: out-of-bounds heap read and crash on NOTIFICATION Cease/Hard Reset with one data byte), 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-2026-129217 (entry last updated 2026-11-13):
Affected:
- FRRouting FRRouting: from 10.5.0, fixed in 10.5.2; from 10.4.0, fixed in 10.4.3; from 10.3, fixed in 10.3.4; from 10.2, fixed in 10.2.6; from 10.1, fixed in 10.1.5; from 8.3, fixed in 10.0.5
Fixed versions: 10.5.2, 10.4.3, 10.3.4, 10.2.6, 10.1.5, 10.0.5.
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
CISA KEV: CVE-2026-129217 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-129217 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/20796
- https://github.com/FRRouting/frr/issues/20793
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-2026-129217
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-2026-129217"}.

Timeline

  1. CVE published
  2. First seen by cve.now

Affected versions

  • FRRouting FRRouting

    From 10.5.0 · fixed in 10.5.2; From 10.4.0 · fixed in 10.4.3; From 10.3 · fixed in 10.3.4; From 10.2 · fixed in 10.2.6; From 10.1 · fixed in 10.1.5; From 8.3 · fixed in 10.0.5

Evidence 4

CVE record · 2

Establishes: The identifier and description.

  1. Record
  2. Record

Other links · 2

  1. Patch
  2. Report

Corrections

None so far.

Something wrong on this page? Report an error. Every fix is listed here.

Questions about CVE-2026-129217

Is CVE-2026-129217 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

Which versions are affected by CVE-2026-129217?

FRRouting: from 10.5.0 before 10.5.2; from 10.4.0 before 10.4.3; from 10.3 before 10.3.4; from 10.2 before 10.2.6; from 10.1 before 10.1.5; from 8.3 before 10.0.5.Source: cve.now feed data

How do I fix CVE-2026-129217?

Upgrade to a fixed version: 10.5.2, 10.4.3, 10.3.4, 10.2.6, 10.1.5, or one of 1 more.Source: cve.now feed data

Sources

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