Pydantic AI: Concurrency-limited models can keep their slot when a streamed request ends early (pydantic pydantic-ai)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.45 % · percentile 39 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- GitHub_M
- NVD 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.
Weaknesses (CWE)
- CWE-772 — Missing Release of Resource after Effective Lifetime
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | HIGH 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | GitHub_M |
| CVSS 3.1 | HIGH 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | NVD · security-advisories@github.com (Secondary) |
Advisories
- GHSA-6fqq-452j-qhrp — Pydantic AI: Concurrency-limited models can keep their slot when a streamed request ends early
- PYSEC-2026-4276 — Pydantic AI: Concurrency-limited models can keep their slot when a streamed request ends early
- PYSEC-2026-4285 — Pydantic AI: Concurrency-limited models can keep their slot when a streamed request ends early
European references
- ENISA EUVD · EUVD-2026-95039
- GCVE · GCVE-0-2026-107286
Affected configurations (NVD CPE)
cpe:2.3:a:pydantic:pydantic_ai:*:-:*:*:*:python:*:*≥ 2.10.0 < 2.53.0
Affected products
| Product | Versions |
|---|---|
| pydantic · pydantic-ai | affected >= 2.10.0, < 2.53.0 |
| pydantic · pydantic-ai-slim | affected >= 2.10.0, < 2.53.0 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |