{"cve":"CVE-2026-107286","nvd":{"published":"2026-10-08T15:17:40.753","modified":"2026-10-13T14:36:51.687","status":"Analyzed","description":"Pydantic AI is a Python agent framework for building applications and workflows with Generative AI. From 2.10.0 until 2.53.0, streamed requests made through ConcurrencyLimitedModel or limit_model_concurrency can retain shared concurrency slots because anyio.CapacityLimiter associates an acquired slot with the borrowing task while streaming cleanup can run in a different task. Early stream termination, cancellation, consumer exceptions, or complete stream_text() consumption with debounce_by=0.1 can therefore leave capacity occupied, eventually preventing later requests that share the long-lived limiter from proceeding and causing a denial of service. Agent-level max_concurrency and non-streaming model requests are not affected. This issue is fixed in version 2.53.0.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-772"],"references":["https://github.com/pydantic/pydantic-ai/commit/453f19feeb7ab1d789f9393b1723c6a73b3d77b2","https://github.com/pydantic/pydantic-ai/pull/9478","https://github.com/pydantic/pydantic-ai/releases/tag/v2.53.0","https://github.com/pydantic/pydantic-ai/security/advisories/GHSA-6fqq-452j-qhrp"],"products":["pydantic:pydantic_ai"],"source":"nvd","synced_at":"2026-10-19T22:58:01.639778232+00:00"},"epss":{"cve":"CVE-2026-107286","score":0.0045,"percentile":0.38808,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-6fqq-452j-qhrp","url":"https://osv.dev/vulnerability/GHSA-6fqq-452j-qhrp","summary":"Pydantic AI: Concurrency-limited models can keep their slot when a streamed request ends early","modified":"2026-10-15T14:55:42.276272043Z","packages":[{"ecosystem":"PyPI","name":"pydantic-ai","purl":"pkg:pypi/pydantic-ai","ranges":[">=2.10.0 <2.53.0"],"fixed":["2.53.0"]},{"ecosystem":"PyPI","name":"pydantic-ai-slim","purl":"pkg:pypi/pydantic-ai-slim","ranges":[">=2.10.0 <2.53.0"],"fixed":["2.53.0"]}]},{"id":"PYSEC-2026-4276","url":"https://osv.dev/vulnerability/PYSEC-2026-4276","summary":"Pydantic AI: Concurrency-limited models can keep their slot when a streamed request ends early","modified":"2026-10-15T14:55:42.276272043Z","packages":[{"ecosystem":"PyPI","name":"pydantic-ai","purl":"pkg:pypi/pydantic-ai","ranges":[">=2.10.0 <2.53.0"],"fixed":["2.53.0"]}]},{"id":"PYSEC-2026-4285","url":"https://osv.dev/vulnerability/PYSEC-2026-4285","summary":"Pydantic AI: Concurrency-limited models can keep their slot when a streamed request ends early","modified":"2026-10-15T14:55:42.276272043Z","packages":[{"ecosystem":"PyPI","name":"pydantic-ai-slim","purl":"pkg:pypi/pydantic-ai-slim","ranges":[">=2.10.0 <2.53.0"],"fixed":["2.53.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}