CVE-2025-62409 - CVE House
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Status published Medium CVE-2025-62409

Envoy allows large requests and responses to cause TCP connection pool crash

Vulnerability Description

Envoy is a cloud-native, open source edge and service proxy. Prior to 1.36.1, 1.35.5, 1.34.9, and 1.33.10, large requests and responses can potentially trigger TCP connection pool crashes due to flow control management in Envoy. It will happen when the connection is closing but upstream data is still coming, resulting in a buffer watermark callback nullptr reference. The vulnerability impacts TCP proxy and HTTP 1 & 2 mixed use cases based on ALPN. This vulnerability is fixed in 1.36.1, 1.35.5, 1.34.9, and 1.33.10.

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

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Credits & Attribution

No credits recorded in the NVD database.

References

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Affected Vendor

Affected Software

envoy
Vulnerable Versions:
>= 1.36.0, < 1.36.1, >= 1.35.0, < 1.35.5, >= 1.34.0, < 1.34.9, < 1.33.10

Timeline

Official Publish: October 16th, 2025
Last Modified: October 16th, 2025
Added to House: July 22nd, 2026

CVSS Vectors

Weaknesses (CWE)

CWE-476

MITRE ATT&CK TTPs

T1499 Endpoint Denial of Service
Impact
T1499.004 Application or System Exploitation
Impact
T1489 Service Stop
Impact
T1203 Exploitation for Client Execution
Execution
T1190 Exploit Public-Facing Application
Initial Access