# CVE-2026-123557: Zebra zebrad before 7.0.0 Reachable Assertion DoS via Peer Disconnection


- **Severity:** High 8.2 (`CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 8 Nov 2026
- **Updated:** 10 Nov 2026
- **Also known as:** GHSA-6v36-c42v-v98p, GHSA-cpwj-fm29-9h32

## What is CVE-2026-123557?

CVE-2026-123557 is a high-severity vulnerability in ZcashFoundation zebra, published on 8 Nov 2026. 

### Official description

ZcashFoundation Zebra zebrad before 7.0.0 contains a reachable assertion race condition that allows unauthenticated remote peers to abort the node by triggering disconnection during a blocked outbound send. Malicious peers can return empty FindBlocks or FindHeaders replies and stop reading their socket, dropping an unresolved MustUseClientResponseSender and terminating syncing nodes.

Weakness: CWE-617 (Reachable Assertion)

## Which versions are affected by CVE-2026-123557?


## How do I fix CVE-2026-123557?

No fix has been published for CVE-2026-123557 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-123557 being exploited?

There is no known exploitation of CVE-2026-123557 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-123557 and fix it if it is affected.

What it is: CVE-2026-123557 is a high-severity vulnerability in ZcashFoundation zebra, published on 8 Nov 2026. 
Exploitation: There is no known exploitation of CVE-2026-123557 in the wild and no public exploit code.

Affected product: ZcashFoundation zebra. 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-2026-123557/ (Markdown: https://insights.sbomify.com/CVE-2026-123557/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-123557
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-123557
- OSV: https://osv.dev/vulnerability/CVE-2026-123557

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-123557/
Summaries are generated and may contain mistakes; the official description above is the record.