# CVE-2026-119776: frr: ospf6d fails to enforce all OSPFv3 packets use IPv6 link-local addresses


- **Severity:** Medium 6.1 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:H/VA:H/SC:N/SI:N/SA:N/AU:Y`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 4 Nov 2026
- **Updated:** 9 Nov 2026
- **Also known as:** AZL-112732, DEBIAN-CVE-2026-119776, GHSA-w6jv-w2m6-2wx3, UBUNTU-CVE-2026-119776

## What is CVE-2026-119776?

CVE-2026-119776 is a medium-severity vulnerability in frrouting, published on 4 Nov 2026. 

### Official description

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.

Required configuration: The OSPFv3 for IPv6 routing protocol must be running (ospf6d process) and in use (enabled globally with "router ospf6" and on specific interfaces with "ipv6 ospf6 area".)

Workaround: either:

  *  configure OSPFv3 authentication trailers ("ipv6 ospf6 authentication")
  *  or ensure through firewall configuration that only packets with link-local or multicast destination addresses are accepted on input for IPv6 protocol 89 (OSPF). Note that checking the source address is insufficient, as some routers may (unexpectedly) forward packets with global-scoped IPv6 destination addresses even if they have link-local source addresses.

Weakness: CWE-304 (Missing Critical Step in Authentication)

## Which versions are affected by CVE-2026-119776?


## How do I fix CVE-2026-119776?

Upgrade to a fixed version.

## Is CVE-2026-119776 being exploited?

There is no known exploitation of CVE-2026-119776 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-119776 and fix it if it is affected.

What it is: CVE-2026-119776 is a medium-severity vulnerability in frrouting, published on 4 Nov 2026. 
Exploitation: There is no known exploitation of CVE-2026-119776 in the wild and no public exploit code.

Affected product: frrouting. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-119776/ (Markdown: https://insights.sbomify.com/CVE-2026-119776/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-119776
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-119776
- OSV: https://osv.dev/vulnerability/CVE-2026-119776

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-119776/
Summaries are generated and may contain mistakes; the official description above is the record.