# CVE-2026-123558: Zebra before 7.0.0 Checkpoint Sync Denial of Service via Cancelled Verifier Rewind


- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/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:** 9 Nov 2026
- **Also known as:** GHSA-2w9f-9wx8-f5c8, GHSA-5hx4-99cr-cchc

## What is CVE-2026-123558?

CVE-2026-123558 is a high-severity vulnerability in ZcashFoundation zebra, published on 8 Nov 2026. 

### Official description

Zebra zebrad before 7.0.0 contains a denial of service vulnerability that allows a malicious peer to stall checkpoint sync by cancelling the verifier rewind after a failed commit. Attackers can serve a forged block with altered authorizing data plus a restart-triggering block, leaving the verifier rejecting honest blocks until restart.

Weakness: CWE-460 (Improper Cleanup on Thrown Exception)

## Which versions are affected by CVE-2026-123558?


## How do I fix CVE-2026-123558?

No fix has been published for CVE-2026-123558 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-123558 being exploited?

There is no known exploitation of CVE-2026-123558 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-123558 and fix it if it is affected.

What it is: CVE-2026-123558 is a high-severity vulnerability in ZcashFoundation zebra, published on 8 Nov 2026. 
Exploitation: There is no known exploitation of CVE-2026-123558 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-2026-123558/ (Markdown: https://insights.sbomify.com/CVE-2026-123558/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-123558
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-123558
- OSV: https://osv.dev/vulnerability/CVE-2026-123558

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-123558/
Summaries are generated and may contain mistakes; the official description above is the record.