{"schemaVersion":3,"id":"CVE-2026-73556","aliases":["GHSA-48jh-3gj7-fg8v","PYSEC-2026-3933","CGA-2489-mm6m-p865","CGA-ch32-rv7r-2f5p","CGA-p8hm-mj4p-3q7x","CGA-vj8w-6mqj-26mg","CGA-vpc5-gmg2-www6"],"status":"published","duplicateOf":null,"title":null,"description":"vLLM is an inference and serving engine for large language models. Prior to 0.26.0, the structured_outputs.regex parameter in vllm/v1/structured_output/backend_lm_format_enforcer.py is passed to lmformatenforcer.RegexParser without compile_regex_with_timeout or validation in validate_structured_output_request_lm_format_enforcer, allowing an unauthenticated /v1/completions request against the lm-format-enforcer backend to consume a CPU core and stall the structured-output engine path with a catastrophic regular expression. This issue is fixed in version 0.26.0.","dates":{"published":"2026-08-13T14:56:52.569Z","modified":"2026-08-14T16:52:40.458Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":5.3,"severity":"medium","version":"3.1","versionLabel":"v3.1","source":"CVE.org","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"CVE.org","score":5.3,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","exploitability":null,"impact":null,"computed":false},{"version":"3.1","versionLabel":"v3.1","source":"OSV · Pypi","score":5.3,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","exploitability":10,"impact":2.3,"computed":true},{"version":"3.1","versionLabel":"v3.1","source":"OSV · Chainguard","score":5.3,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","exploitability":10,"impact":2.3,"computed":true},{"version":"3.1","versionLabel":"v3.1","source":"NVD","score":5.3,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","exploitability":null,"impact":null,"computed":false}]},"epss":{"probability":0.00515,"percentile":0.42967,"severity":"low","asOf":"2026-10-21T00:00:00.000Z","change":{"pp":0.2,"baselineDate":"2026-09-21T00:00:00.000Z","baselineScore":0.00315},"history":[{"date":"2026-09-14T00:00:00.000Z","score":0.00315,"percentile":null},{"date":"2026-09-15T00:00:00.000Z","score":0.00315,"percentile":null},{"date":"2026-09-16T00:00:00.000Z","score":0.00315,"percentile":null},{"date":"2026-09-17T00:00:00.000Z","score":0.00315,"percentile":null},{"date":"2026-09-18T00:00:00.000Z","score":0.00315,"percentile":null},{"date":"2026-09-19T00:00:00.000Z","score":0.00315,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.00315,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.00315,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.00315,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.00315,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.00524,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.00524,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.00524,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.00524,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.00524,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-20T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-21T00:00:00.000Z","score":0.00515,"percentile":0.42967}],"last30":[{"date":"2026-09-21T00:00:00.000Z","score":0.00315,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.00315,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.00315,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.00524,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.00524,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.00524,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.00524,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.00524,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-20T00:00:00.000Z","score":0.00515,"percentile":null},{"date":"2026-10-21T00:00:00.000Z","score":0.00515,"percentile":0.42967}]},"kev":{"state":"not-listed","entries":[],"listedCount":0,"totalCatalogs":3,"catalogs":[{"source":"cisa","label":"CISA","listed":false,"entry":null},{"source":"enisa","label":"ENISA","listed":false,"entry":null},{"source":"circl","label":"CIRCL","listed":false,"entry":null}]},"ransomware":{"state":"none-recorded","sources":[]},"exploits":[],"exploitCount":0,"weaknesses":[{"id":"CWE-400","name":"Uncontrolled Resource Consumption","description":"The product does not properly control the allocation and maintenance of a limited resource.","type":"weakness","status":"Draft","abstraction":"Class","likelihoodOfExploit":"High","url":"https://cwe.mitre.org/data/definitions/400.html"},{"id":"CWE-1333","name":"Inefficient Regular Expression Complexity","description":"The product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential.","type":"weakness","status":"Draft","abstraction":"Base","likelihoodOfExploit":"High","url":"https://cwe.mitre.org/data/definitions/1333.html"}],"affected":[{"vendor":"chainguard","product":"kserve-huggingfaceserver-cuda-13.3","name":"kserve-huggingfaceserver-cuda-13.3","label":"kserve-huggingfaceserver-cuda-13.3","ecosystem":"Chainguard","cpePart":null,"purl":"pkg:apk/chainguard/kserve-huggingfaceserver-cuda-13.3","purlType":"apk","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null},{"vendor":"chainguard","product":"lmcache-cuda-12.8","name":"lmcache-cuda-12.8","label":"lmcache-cuda-12.8","ecosystem":"Chainguard","cpePart":null,"purl":"pkg:apk/chainguard/lmcache-cuda-12.8","purlType":"apk","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null},{"vendor":"chainguard","product":"nemo-rl-cuda-13.0-vllm","name":"nemo-rl-cuda-13.0-vllm","label":"nemo-rl-cuda-13.0-vllm","ecosystem":"Chainguard","cpePart":null,"purl":"pkg:apk/chainguard/nemo-rl-cuda-13.0-vllm","purlType":"apk","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null},{"vendor":"chainguard","product":"py3.10-vllm-cuda-12.4","name":"py3.10-vllm-cuda-12.4","label":"py3.10-vllm-cuda-12.4","ecosystem":"Chainguard","cpePart":null,"purl":"pkg:apk/chainguard/py3.10-vllm-cuda-12.4","purlType":"apk","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null},{"vendor":"chainguard","product":"py3.12-vllm-cuda-12.4","name":"py3.12-vllm-cuda-12.4","label":"py3.12-vllm-cuda-12.4","ecosystem":"Chainguard","cpePart":null,"purl":"pkg:apk/chainguard/py3.12-vllm-cuda-12.4","purlType":"apk","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null},{"vendor":"PyPI","product":"vllm","name":"vllm","label":"vllm","ecosystem":"PyPI","cpePart":null,"purl":"pkg:pypi/vllm","purlType":"pypi","versions":[{"text":"< 0.26.0","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 0.26.0","eol":null,"hubHref":null},{"vendor":"vllm-project","product":"vllm","name":"vllm","label":"vllm","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"< 0.26.0","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 0.26.0","eol":null,"hubHref":"/vendor/vllm-project/vllm"},{"vendor":"vllm","product":"vllm","name":"vllm","label":"vllm","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"< 0.26.0","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 0.26.0","eol":null,"hubHref":"/vendor/vllm/vllm"}],"affectedCount":8,"eol":{"hasEol":false,"count":0},"references":[{"url":"https://github.com/vllm-project/vllm/security/advisories/GHSA-48jh-3gj7-fg8v","label":"github.com/vllm-project/vllm/security/advisories/GHSA-48jh-3gj7-fg8v","hostname":"github.com","tags":["X Refsource CONFIRM","WEB","Advisory","Vendor Advisory"]},{"url":"https://github.com/vllm-project/vllm/pull/47595","label":"github.com/vllm-project/vllm/pull/47595","hostname":"github.com","tags":["X Refsource MISC","WEB","FIX","Issue Tracking","Patch"]},{"url":"https://github.com/vllm-project/vllm/commit/c9a788eedc412acceaa5112e0d44624b49841577","label":"github.com/vllm-project/vllm/commit/c9a788eedc412acceaa5112e0d44624b49841577","hostname":"github.com","tags":["X Refsource MISC","WEB","FIX","Patch"]},{"url":"https://github.com/vllm-project/vllm/releases/tag/v0.26.0","label":"github.com/vllm-project/vllm/releases/tag/v0.26.0","hostname":"github.com","tags":["X Refsource MISC","WEB","Release Notes"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-73556","label":"nvd.nist.gov/vuln/detail/CVE-2026-73556","hostname":"nvd.nist.gov","tags":["Advisory"]},{"url":"https://github.com/vllm-project/vllm","label":"github.com/vllm-project/vllm","hostname":"github.com","tags":["PACKAGE"]},{"url":"https://pypi.org/project/vllm","label":"pypi.org/project/vllm","hostname":"pypi.org","tags":["PACKAGE"]},{"url":"https://github.com/advisories/GHSA-48jh-3gj7-fg8v","label":"github.com/advisories/GHSA-48jh-3gj7-fg8v","hostname":"github.com","tags":["Advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73556.json","label":"github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73556.json","hostname":"github.com","tags":["Advisory"]}],"lineage":{"upstream":[],"downstream":[],"duplicates":[],"related":[]},"timeline":[{"kind":"published","date":"2026-08-13T14:56:52.569Z","label":"Published","detail":"Vulnerability first disclosed.","source":null},{"kind":"modified","date":"2026-08-14T16:52:40.458Z","label":"Last modified","detail":"Vulnerability information updated.","source":null}],"risk":{"score":21,"level":"low","profile":"Default","thresholds":{"critical":75,"high":50,"medium":25,"low":10}},"meta":{"dataAsOf":"2026-10-22T13:49:16.231Z","stale":false,"partial":false}}