# CVE-2025-9556: CVE-2025-9556

> Attackers can exploit server-side template injection in Langchaingo to read sensitive files like /etc/passwd via malicious prompts.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 Sep 2025
- **Updated:** 3 Nov 2025
- **Also known as:** GHSA-mgcj-g55g-rf6h, GHSA-v6f2-g4gw-r4rc

## What is CVE-2025-9556?

CVE-2025-9556 is a critical code injection vulnerability in Langchaingo, published on 12 Sep 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Langchaingo supports the use of jinja2 syntax when parsing prompts, which is in turn parsed using the gonja library v1.5.3.
Gonja supports include and extends syntax to read files, which leads to a server side template injection vulnerability within langchaingo, allowing an attacker to insert a statement into a prompt to read the "etc/passwd" file.

## Which versions are affected by CVE-2025-9556?


## How do I fix CVE-2025-9556?

No fix has been published for CVE-2025-9556 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-9556 being exploited?

There is no known exploitation of CVE-2025-9556 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-9556 and fix it if it is affected.

What it is: CVE-2025-9556 is a critical code injection vulnerability in Langchaingo, published on 12 Sep 2025. 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-2025-9556 in the wild and no public exploit code.

Affected product: Langchaingo. 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-2025-9556/ (Markdown: https://insights.sbomify.com/CVE-2025-9556/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-9556
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-9556
- OSV: https://osv.dev/vulnerability/CVE-2025-9556

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-9556/
Summaries are generated and may contain mistakes; the official description above is the record.