CVE-2026-107286: CWE-772: Missing Release of Resource after Effective Lifetime in pydantic pydantic-ai
Description
CVE-2026-107286 is a resource management vulnerability in pydantic-ai versions from 2.10.0 up to but not including 2.53.0. The issue arises when streamed requests using ConcurrencyLimitedModel or limit_model_concurrency retain concurrency slots due to task association mismatches in anyio.CapacityLimiter. This can cause capacity to remain occupied after early stream termination or cancellation, leading to denial of service by blocking subsequent requests sharing the same limiter. The vulnerability does not affect agent-level max_concurrency or non-streaming model requests. The issue is fixed in version 2.53.0.
CVSS v3.1
Score 7.5high
Affected software
pydantic
pydantic-ai
pydantic
pydantic-ai-slim
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Pydantic AI, a Python framework for Generative AI applications, has a vulnerability (CVE-2026-107286) classified as CWE-772 (Missing Release of Resource after Effective Lifetime). In versions >=2.10.0 and <2.53.0, streamed requests made through ConcurrencyLimitedModel or limit_model_concurrency can retain shared concurrency slots improperly because anyio.CapacityLimiter associates slots with the borrowing task, but streaming cleanup may run in a different task. Early termination, cancellation, or consumer exceptions can leave capacity occupied, eventually preventing later requests from proceeding and causing denial of service. Non-streaming requests and agent-level max_concurrency are unaffected. The vulnerability is resolved in version 2.53.0.
Potential Impact
The vulnerability can cause denial of service by exhausting concurrency slots in the CapacityLimiter, preventing new streamed requests from proceeding when shared concurrency slots remain occupied due to improper release after early stream termination or cancellation. There is no impact on confidentiality or integrity, only availability is affected.
Mitigation Recommendations
Upgrade pydantic-ai to version 2.53.0 or later, where this issue is fixed. No other mitigation is required as the fix addresses the root cause.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-10-07T15:53:23.586Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6ac7b46a2cdf04f656230dc7
Added to database: 10/08/2026, 15:19:06 UTC
Last enriched: 10/08/2026, 15:33:26 UTC
Last updated: 10/08/2026, 15:36:12 UTC
Views: 5
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