Advisory details:
pypa / vllm/PYSEC-2026-2021
| Advisory ID | pypa/vllm/PYSEC-2026-2021 |
| Aliases |
CVE-2025-48956
GHSA-rxc4-3w6r-4v47 PYSEC-2026-2021 |
| Summary | vllm API endpoints vulnerable to Denial of Service Attacks ### Summary A Denial of Service (DoS) vulnerability can be triggered by sending a single HTTP GET request with an extremely large header to an HTTP endpoint. This results in server memory exhaustion, potentially leading to a crash or unresponsiveness. The attack does not require authentication, making it exploitable by any remote user. ### Details The vulnerability leverages the abuse of HTTP headers. By setting a header such as `X-Forwarded-For` to a very large value like `("A" * 5_800_000_000)`, the server's HTTP parser or application logic may attempt to load the entire request into memory, overwhelming system resources. ### Impact _What kind of vulnerability is it? Who is impacted?_ Type of vulnerability: Denial of Service (DoS) ### Resolution Upgrade to a version of vLLM that includes appropriate HTTP limits by deafult, or use a proxy in front of vLLM which provides protection against this issue. |
| Status | Published |
| Exploitability | 0.5 |
| Weighted Severity | 6.8 |
| Risk | 3.4 |
| Affected and Fixed Packages | Package Details |
| Introduced and Fixed Package Commit Patches | Package Commit Patches Details |
| There are no known CWE. |
| System | Score | Found at |
|---|---|---|
| cvssv3.1 | 7.5 | https://github.com/pypa/advisory-database/blob/main/vulns/vllm/PYSEC-2026-2021.yaml |
| Reference id | Reference type | URL |
|---|---|---|
| https://github.com/vllm-project/vllm | ||
| https://github.com/vllm-project/vllm/commit/d8b736f913a59117803d6701521d2e4861701944 | ||
| https://github.com/vllm-project/vllm/pull/23267 | ||
| https://pypi.org/project/vllm | ||
| CVE-2025-48956 | https://nvd.nist.gov/vuln/detail/CVE-2025-48956 | |
| GHSA-rxc4-3w6r-4v47 | https://github.com/advisories/GHSA-rxc4-3w6r-4v47 | |
| GHSA-rxc4-3w6r-4v47 | https://github.com/vllm-project/vllm/security/advisories/GHSA-rxc4-3w6r-4v47 |
No EPSS data available for this advisory.
| Patch URL | |
|---|---|
| There are no known patches. | |
| Attack Vector (AV) | Attack Complexity (AC) | Privileges Required (PR) | User Interaction (UI) | Scope (S) | Confidentiality Impact (C) | Integrity Impact (I) | Availability Impact (A) |
|---|---|---|---|---|---|---|---|
network adjacent_network local physical |
low high |
none low high |
none required |
unchanged changed |
high low none |
high low none |
high low none |
Vector: SSVCv2/E:N/A:Y/T:P/P:M/B:A/M:M/D:T/2025-08-21T15:01:51Z/
Decision: Track
Source URL: https://github.com/cisagov/vulnrichment/blob/develop/2025/48xxx/CVE-2025-48956.json
Source Advisory: vulnrichment/CVE-2025-48956
[{'Exploitation': 'none'},
{'Automatable': 'yes'},
{'Technical Impact': 'partial'},
{'Mission Prevalence': 'minimal'},
{'Public Well-being Impact': 'material'},
{'Mission & Well-being': 'medium'}]