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Medium, CVSS 6.5amended

vLLM has a Regular Expression Denial of Service (ReDoS, Exponential Complexity) Vulnerability in pythonic_tool_parser.py

CVE-2025-48887GHSA-w6q7-j642-7c25

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (vllm 0.9.0), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • PyPI vllm

    Affected
    >= 0.6.4, < 0.9.0
    Fixed in
    0.9.0

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
6.5 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS
  • CVE-2025-48887: 0.54% estimated exploitation activity in the next 30 days; percentile 45.53 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary A Regular Expression Denial of Service (ReDoS) vulnerability exists in the file vllm/entrypoints/openai/toolparsers/pythonictoolparser.py of the vLLM project. The root cause is the use of a highly complex and nested regular expression for tool call detection, which can be exploited by an attacker to cause severe performance degradation or make the service unavailable. Details The following regular expression is used to match tool/function call patterns: This pattern contains multiple nested quantifiers (, +), optional groups, and inner repetitions which make it vulnerable to catastrophic backtracking. Attack Example: A malicious input such as can cause the regular expression engine to consume CPU exponentially with the input length, effectively freezing or crashing the server (DoS). Proof of Concept: A Python script demonstrates that matching such a crafted string with the above regex results in exponential time complexity. Even moderate input lengths can bring the system to…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-w6q7-j642-7c25

  2. Revision 1 · created ·

    Published from osv record GHSA-w6q7-j642-7c25

Agent brief

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# Patch Next advisory brief: CVE-2025-48887

Advisory: vLLM has a Regular Expression Denial of Service (ReDoS, Exponential Complexity) Vulnerability in `pythonic_tool_parser.py`
IDs: CVE-2025-48887, GHSA-w6q7-j642-7c25
Record: https://patchnext.com/advisories/cve-2025-48887 (revision 2, source checked 26 Oct 2026, 13:32 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: vllm 0.9.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI vllm: affected >= 0.6.4, < 0.9.0; fixed in 0.9.0

## Suggested inspection (read-only)
- `python -m pip show vllm`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on vllm.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-w6q7-j642-7c25 (OSV record GHSA-w6q7-j642-7c25 lists affected ranges: PyPI vllm >=0.6.4 <0.9.0 (fixed))
- Verified: https://github.com/advisories/GHSA-w6q7-j642-7c25 (GitHub-reviewed advisory GHSA-w6q7-j642-7c25 lists affected ranges: PyPI vllm >=0.6.4 <0.9.0)

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