High severity · published Oct 16, 2025
CVE-2025-62409
Envoy allows large requests and responses to cause TCP connection pool crash
7.5
CVSS
0.5%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 39% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
EN
envoy · envoyproxy
>= 1.36.0, < 1.36.1; >= 1.35.0, < 1.35.5; >= 1.34.0, < 1.34.9; < 1.33.10 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-62409
CVE.org
https://www.cve.org/CVERecord?id=CVE-2025-62409
Vendor Advisory
https://github.com/envoyproxy/envoy/security/advisories/GHSA-pq33-4jxh-hgm3
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