{"id":"CVE-2025-48956","aliases":["GHSA-rxc4-3w6r-4v47","PYSEC-2026-2021"],"url":"https://o3.security/vulnerability/CVE-2025-48956","summary":"vLLM API endpoints vulnerable to Denial of Service Attacks","details":"### Summary\nA 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.\n\n### Details\nThe 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.\n\n### Impact\n_What kind of vulnerability is it? Who is impacted?_\nType of vulnerability: Denial of Service (DoS)\n\n### Resolution\nUpgrade 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.","published":"2025-08-21T14:41:03.889Z","modified":"2026-08-12T03:51:36.874377845Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":{"score":0.00556,"percentile":0.43516,"asOf":"2026-08-13"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"vllm","fixedVersion":"0.10.1.1"}],"fix":{"url":"https://github.com/vllm-project/vllm/commit/d8b736f913a59117803d6701521d2e4861701944","label":"vllm-project/vllm@d8b736f"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/48xxx/CVE-2025-48956.json"},{"type":"ADVISORY","url":"https://github.com/vllm-project/vllm/security/advisories/GHSA-rxc4-3w6r-4v47"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-48956"},{"type":"FIX","url":"https://github.com/vllm-project/vllm/commit/d8b736f913a59117803d6701521d2e4861701944"},{"type":"FIX","url":"https://github.com/vllm-project/vllm/pull/23267"},{"type":"ADVISORY","url":"https://github.com/advisories/GHSA-rxc4-3w6r-4v47"},{"type":"WEB","url":"https://github.com/pypa/advisory-database/tree/main/vulns/vllm/PYSEC-2026-2021.yaml"},{"type":"PACKAGE","url":"https://github.com/vllm-project/vllm"},{"type":"WEB","url":"https://pypi.org/project/vllm"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:36.874377845Z"}}