# CVE-2026-2379: Arista EOS IPsec Tunnel Sequence Number Mismatch via Interface Flaps when Anti-Replay is Disabled

> Interface flaps can cause IPsec sequence number mismatches leading to unstable communication and potential denial of service on Arista EOS devices.

- **Severity:** High 8.2 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 5 Jun 2026
- **Updated:** 9 Jun 2026
- **Also known as:** GHSA-qm38-553v-42w8

## What is CVE-2026-2379?

CVE-2026-2379 is a high-severity denial of service vulnerability in Arista Networks EOS, published on 5 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

On affected platforms with hardware IPSec support running Arista EOS with certain IPsec features enabled, EOS may exhibit unexpected behavior in specific cases. Physical interface flaps and certain agent restarts can cause IPsec tunnel re-establishment with existing Security Associations, resulting in sequence number mismatches between tunnel endpoints potentially causing unstable communication.

Weakness: CWE-672 (Operation on a Resource after Expiration or Release)

## Which versions are affected by CVE-2026-2379?


## How do I fix CVE-2026-2379?

No fix has been published for CVE-2026-2379 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-2379 being exploited?

There is no known exploitation of CVE-2026-2379 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-2379 and fix it if it is affected.

What it is: CVE-2026-2379 is a high-severity denial of service vulnerability in Arista Networks EOS, published on 5 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-2379 in the wild and no public exploit code.

Affected product: Arista Networks EOS. 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-2026-2379/ (Markdown: https://insights.sbomify.com/CVE-2026-2379/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-2379
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-2379
- OSV: https://osv.dev/vulnerability/CVE-2026-2379

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-2379/
Summaries are generated and may contain mistakes; the official description above is the record.