CVE-2026-107286
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 3.1
- 7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - EPSS
- 0.4% chance of exploitation in the next 30 days; higher than 38% of CVEs (scores of 2026-10-25)
- CWE
- CWE-772
- Published
- Modified
- Record from
- the NVD, synced
Affected
- pydantic:pydantic_ai
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-6fqq-452j-qhrp | PyPI | pydantic-ai | >=2.10.0 <2.53.0 | 2.53.0 |
| GHSA-6fqq-452j-qhrp | PyPI | pydantic-ai-slim | >=2.10.0 <2.53.0 | 2.53.0 |
| PYSEC-2026-4276 | PyPI | pydantic-ai | >=2.10.0 <2.53.0 | 2.53.0 |
| PYSEC-2026-4285 | PyPI | pydantic-ai-slim | >=2.10.0 <2.53.0 | 2.53.0 |