---
id: "CVE-2026-119776"
kind: "vulnerability"
aliases: ["CVE-2026-119776"]
title: "FRRouting: OSPFv3 accepts packets from non-link-local IPv6 hosts"
severity: "medium"
cvss: 6.1
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["frrouting", "ipv6", "ospfv3", "routers", "runtime"]
not_affected_if: ["no-ospfv3", "ospf-authentication-trailers"]
published_at: "2026-11-04T15:17:41+00:00"
first_seen_at: "2026-11-04T15:27:29+00:00"
updated_at: "2026-11-04T15:28:28+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-119776", "first_seen_at": "2026-11-04T15:27:29+00:00"}]
---

# FRRouting: OSPFv3 accepts packets from non-link-local IPv6 hosts

FRRouting's OSPFv3 implementation for IPv6 does not check that packets come from a link-local source and go to a link-local or protocol multicast destination. An attacker on a distant IPv6 host can establish OSPFv3 adjacencies with the router, and authentication trailers (RFC 7166) limit full exploitation but can still be used to waste CPU.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the FRRouting version with `vtysh -c 'show version'`; all prior released versions are listed as affected in the description.
- Check whether OSPFv3 is enabled with `vtysh -c 'show ipv6 ospf6 interface'`.
- Check whether OSPFv3 authentication trailers are configured on the interfaces.

## Timeline

- 2026-11-04T15:27:29+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-119776

## From the sources

In all prior released versions of FRRouting, the OSPFv3 (for IPv6) implementation does not check that OSPFv3 packets have a link-local source address and either a link-local destination or one of the protocol multicast destination groups.  This may enable malicious actors to establish OSPFv3 adjacencies from unexpectedly, distant IPv6 hosts. Proper usage of OSPFv3 authentication trailers (RFC 7166, as is best practice) prevents full exploitation of this issue, though may allow a malicious actor to waste CPU on authentication checks.



Note the linked PR #23935 is not sufficient to fix the issue as it only verifies the source address. It is the destination address that must be checked.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_