How severe is CVE-2025-6518?

No CVSS score has been assigned to CVE-2025-6518 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2025-6518?

CVE-2025-6518 affects the following packages: pyspur (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2025-6518?

The records we use list no patched version of pyspur for CVE-2025-6518. Check the maintainer's advisory, and where your build allows, override or pin the dependency away from the vulnerable range.

How do I detect CVE-2025-6518 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pyspur, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2025-6518 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is CVE-2025-6518 actively exploited in the wild?

No public exploit code has been indexed for CVE-2025-6518 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2025-6518?

CVE-2025-6518 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 34th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2025-6518?

CVE-2025-6518 is classified as CWE-791 (CWE-791), CWE-1336 (CWE-1336). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2025-6518 published, and has it been updated?

CVE-2025-6518 was published on June 23, 2025 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2025-6518: pyspur

Exploitation Status

Proof-of-concept exploit code exists

CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.

Exploitation and automatability from CISA’s SSVC triage for CVE-2025-6518.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs34th percentile — riskier than 34% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

🐍pyspur

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

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.

Affected Packages

1 total

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`pyspur`	all versions	No fix

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pyspur, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
The records we use list no patched version of pyspur for CVE-2025-6518. Check the maintainer's advisory, and where your build allows, override or pin the dependency away from the vulnerable range.
Mitigate without a patch
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

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.

O3 Security · Impact-Aware SCA

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CVE-2025-6518 — pyspur