CVE-2025-62409: envoy Null Dereference — Fix

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.

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CVSS v3.1 Score

7.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-476 CWE-476

Affected Products

Vendor	Product	Versions
envoyproxy	envoy	< 1.33.11
envoyproxy	envoy	1.34.0 — 1.34.9
envoyproxy	envoy	1.35.0 — 1.35.5
envoyproxy	envoy	All

References

Advisories & Patches

https://github.com/envoyproxy/envoy/security/advisories/GHSA-pq33-4jxh-hgm3 https://github.com/envoyproxy/envoy/security/advisories/GHSA-pq33-4jxh-hgm3

Frequently Asked Questions

What is CVE-2025-62409? +

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. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2025-62409? +

CVE-2025-62409 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2025-62409? +

CVE-2025-62409 affects products from envoyproxy, specifically: envoy. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-62409? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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