# CVE-2025-6518: PySpur-Dev pyspur Jinja2 Template single_llm_call.py SingleLLMCallNode special elements used in a template engine

> Remote attackers can execute arbitrary code via Jinja2 template injection in the SingleLLMCallNode user_message argument.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 23 Jun 2025
- **Updated:** 23 Jun 2025
- **Also known as:** GHSA-8gff-cf92-72pv, PYSEC-2026-1844

## What is CVE-2025-6518?

CVE-2025-6518 is a medium-severity code injection vulnerability in PySpur-Dev pyspur, published on 23 Jun 2025. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A vulnerability was found in PySpur-Dev pyspur up to 0.1.18. It has been classified as critical. Affected is the function SingleLLMCallNode of the file backend/pyspur/nodes/llm/single_llm_call.py of the component Jinja2 Template Handler. The manipulation of the argument user_message leads to improper neutralization of special elements used in a template engine. It is possible to launch the attack remotely. The exploit has been disclosed to the public and may be used.

Weakness: CWE-791 (Incomplete Filtering of Special Elements), CWE-1336 (Improper Neutralization of Special Elements Used in a Template Engine)

## Which versions are affected by CVE-2025-6518?

3 open source packages ship an affected version, including pyspur.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `pyspur` | PyPI | All versions to 0.1.18 | None |
| `pyspur` | PyPI | All versions to 0.1.18 | None |
| `pyspur` | PyPI | All versions to 0.1.18 | None |

## How do I fix CVE-2025-6518?

No fix has been published for CVE-2025-6518 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-6518 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-6518 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-6518 and fix it if it is affected.

What it is: CVE-2025-6518 is a medium-severity code injection vulnerability in PySpur-Dev pyspur, published on 23 Jun 2025. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-6518 exists.

Affected packages and fixed versions:
- pyspur (PyPI): affected all versions up to 0.1.18; no fix listed
- pyspur (PyPI): affected all versions up to 0.1.18; no fix listed
- pyspur (PyPI): affected all versions up to 0.1.18; no fix listed

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-2025-6518/ (Markdown: https://insights.sbomify.com/CVE-2025-6518/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-6518
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-6518
- OSV: https://osv.dev/vulnerability/CVE-2025-6518

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-6518/
Summaries are generated and may contain mistakes; the official description above is the record.