{"id":"CVE-2025-32381","aliases":["GHSA-389x-67px-mjg3","PYSEC-2025-235"],"title":"xgrammar Vulnerable to Denial of Service (DoS) by abusing unbounded cache in memory","summary":"xgrammar Vulnerable to Denial of Service (DoS) by abusing unbounded cache in memory","severity":"medium","cvss":6.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","vendor":"xgrammar","product":"xgrammar","ecosystem":"pip","affected":["xgrammar < 0.1.18"],"patched":["xgrammar 0.1.18"],"published":"2025-04-09","updated":"2026-09-10","sourceUpdated":"2026-09-10T03:50:57.150873872Z","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-389x-67px-mjg3","references":[{"url":"https://github.com/mlc-ai/xgrammar/security/advisories/GHSA-389x-67px-mjg3"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2025-32381"},{"url":"https://github.com/mlc-ai/xgrammar/pull/243"},{"url":"https://github.com/vllm-project/vllm/pull/16283"},{"url":"https://github.com/mlc-ai/xgrammar"},{"url":"https://github.com/pypa/advisory-database/tree/main/vulns/xgrammar/PYSEC-2025-235.yaml"}],"tags":["osv","pip"],"epss":0.00498,"epssPercentile":0.41779,"ingestedAt":"2026-08-07T19:14:13.849Z","slug":"CVE-2025-32381","body":"## Overview\n\n### Summary\n\nXgrammar includes a cache for compiled grammars to increase performance with repeated use of the same grammar. This cache is held in memory. Since the cache is unbounded, a system making use of xgrammar can be abused to fill up a host's memory and case a denial of service. For example, sending many small requests to an LLM inference server with unique JSON schemas would eventually cause this denial of service to occur.\n\n### Details\n\nThe fix is to add a limit to the cache size. This was done in https://github.com/mlc-ai/xgrammar/pull/243\n\nAn example of making use of the new cache size limit can be found in vLLM here: https://github.com/vllm-project/vllm/pull/16283\n\n### Impact\n\nAny system making use of Xgrammar and taking requests as input from potentially untrusted parties would be vulnerable to this denial of service issue.\n\n## Affected packages\n\n- `xgrammar < 0.1.18`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `xgrammar 0.1.18`","depth":"sunlit","depthScore":36,"depthScoreParts":{"impact":35.8,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}