CVE-2026-107286
Pydantic AI is a Python agent framework for building applications and workflows with Generative AI.
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | pydantic-ai | >= 2.10.0, < 2.53.0 | 2.53.0 |
| pip | pydantic-ai-slim | >= 2.10.0, < 2.53.0 | 2.53.0 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Pydantic | Pydantic Ai | from 2.10.0 before 2.53.0 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-6fqq-452j-qhrp
- https://github.com/pydantic/pydantic-ai/security/advisories/GHSA-6fqq-452j-qhrp
- https://nvd.nist.gov/vuln/detail/CVE-2026-107286
- https://github.com/pydantic/pydantic-ai/pull/9478
- https://github.com/pydantic/pydantic-ai/commit/453f19feeb7ab1d789f9393b1723c6a73b3d77b2
- https://github.com/pydantic/pydantic-ai/releases/tag/v2.53.0