# CVE-2026-123870: The otterdog webapp evaluates a format-string built from the incoming GitHub webhook JSON body using Python's eval().


- **Severity:** Critical 9.5 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 9 Nov 2026
- **Updated:** 12 Nov 2026
- **Also known as:** GHSA-32xf-7j44-xq72

## What is CVE-2026-123870?

CVE-2026-123870 is a critical vulnerability in Eclipse Foundation otterdog, published on 9 Nov 2026. 

### Official description

The otterdog webapp evaluates a format-string built from the incoming GitHub webhook JSON body using Python's eval(). When the GITHUB_WEBHOOK_SECRET configuration value is unset or empty (the code default is None), the HMAC signature check is skipped entirely, allowing an unauthenticated network client to reach the eval() sink with attacker-controlled input and execute arbitrary Python on the webapp host.

Weakness: CWE-95 (Improper Neutralization of Directives in Dynamically Evaluated Code)

## Which versions are affected by CVE-2026-123870?


## How do I fix CVE-2026-123870?

No fix has been published for CVE-2026-123870 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-123870 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-123870 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-123870 and fix it if it is affected.

What it is: CVE-2026-123870 is a critical vulnerability in Eclipse Foundation otterdog, published on 9 Nov 2026. 
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-123870 exists.

Affected product: Eclipse Foundation otterdog. 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-2026-123870/ (Markdown: https://insights.sbomify.com/CVE-2026-123870/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-123870
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-123870
- OSV: https://osv.dev/vulnerability/CVE-2026-123870

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-123870/
Summaries are generated and may contain mistakes; the official description above is the record.