GHSA-6fqq-452j-qhrp: pydantic-ai (CVE-2026-107286)

Package	Ecosystem	Affected	Fixed in
pydantic-ai	PyPI	>=2.10.0, <2.53.0	2.53.0
pydantic-ai-slim	PyPI	>=2.10.0, <2.53.0	2.53.0

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Pydantic AI's concurrency-limited models (ConcurrencyLimitedModel and limit_model_concurrency) in pydantic-ai and pydantic-ai-slim versions 2.10.0 up to, but not including, 2.53.0 can permanently lose shared concurrency slots when a streamed request ends early or is fully consumed with default stream_text() debouncing. A remote client that repeatedly starts a stream and disconnects could eventually block later requests sharing the limiter. Upgrade to pydantic-ai or pydantic-ai-slim 2.53.0 or later; alternatively, use agent-level max_concurrency instead.

Written 1 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
7.5	High	3.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	CNA (GitHub_M)

CISA KEV Not listed.
EPSS 0.0045, the 39th percentile, on 8 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

31 Oct 2026, 14:08 UTC First seen by agentprime
31 Oct 2026, 14:08 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.