Envoy up to 1.33.11/1.34.9/1.35.5/1.36.1 per_connection_buffer_limit_bytes use after free

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
6.0	$0-$5k	0.00

Summaryinfo

A vulnerability was found in Envoy up to 1.33.11/1.34.9/1.35.5/1.36.1 and classified as critical. The affected element is the function per_connection_buffer_limit_bytes. Executing a manipulation can lead to use after free. This vulnerability is handled as CVE-2025-62504. The attack can be executed remotely. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in Envoy up to 1.33.11/1.34.9/1.35.5/1.36.1. This vulnerability affects the function per_connection_buffer_limit_bytes. The manipulation with an unknown input leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect availability. CVE summarizes:

Envoy is an open source edge and service proxy. Envoy versions earlier than 1.36.2, 1.35.6, 1.34.10, and 1.33.12 contain a use-after-free vulnerability in the Lua filter. When a Lua script executing in the response phase rewrites a response body so that its size exceeds the configured per_connection_buffer_limit_bytes (default 1MB), Envoy generates a local reply whose headers override the original response headers, leaving dangling references and causing a crash. This results in denial of service. Updating to versions 1.36.2, 1.35.6, 1.34.10, or 1.33.12 fixes the issue. Increasing per_connection_buffer_limit_bytes (and for HTTP/2 the initial_stream_window_size) or increasing per_request_buffer_limit_bytes / request_body_buffer_limit can reduce the likelihood of triggering the condition but does not correct the underlying memory safety flaw.

The advisory is available at github.com. This vulnerability was named CVE-2025-62504 since 10/15/2025. The exploitation appears to be easy. The attack can be initiated remotely. Technical details are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 281808 (Amazon Linux 2 : ecs-service-connect-agent, --advisory ALAS2ECS-2025-093 (ALASECS-2025-093)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 1.33.12, 1.34.10, 1.35.6 or 1.36.2 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (281808) and CERT Bund (WID-SEC-2025-2433). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Affected

• Amazon Linux 2
• Google Cloud Platform

Productinfo

Name

• Envoy

Version

• 1.33.0
• 1.33.1
• 1.33.2
• 1.33.3
• 1.33.4
• 1.33.5
• 1.33.6
• 1.33.7
• 1.33.8
• 1.33.9
• 1.33.10
• 1.33.11
• 1.34.0
• 1.34.1
• 1.34.2
• 1.34.3
• 1.34.4
• 1.34.5
• 1.34.6
• 1.34.7
• 1.34.8
• 1.34.9
• 1.35.0
• 1.35.1
• 1.35.2
• 1.35.3
• 1.35.4
• 1.35.5
• 1.36.0
• 1.36.1

License

• free

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.1
VulDB Meta Temp Score: 6.0

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 7.5
NVD Vector: 🔒

CNA Base Score: 6.5
CNA Vector (GitHub_M): 🔒

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 281808
Nessus Name: Amazon Linux 2 : ecs-service-connect-agent, --advisory ALAS2ECS-2025-093 (ALASECS-2025-093)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Envoy 1.33.12/1.34.10/1.35.6/1.36.2

Timelineinfo

10/15/2025 CVE reserved
10/17/2025 +2 days Advisory disclosed
10/17/2025 +0 days VulDB entry created
01/07/2026 +82 days VulDB entry last update

Sourcesinfo

Advisory: GHSA-gcxr-6vrp-wff3
Status: Confirmed

CVE: CVE-2025-62504 (🔒)
GCVE (CVE): GCVE-0-2025-62504
GCVE (VulDB): GCVE-100-328906
CERT Bund: WID-SEC-2025-2433 - Google Cloud Platform (Envoy Proxy):: Mehrere Schwachstellen ermöglichen Denial of Service

Entryinfo

Created: 10/17/2025 08:06
Updated: 01/07/2026 05:59
Changes: 10/17/2025 08:06 (64), 10/30/2025 00:32 (11), 10/30/2025 03:33 (7), 01/06/2026 12:59 (2), 01/07/2026 05:59 (1)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Discussion

Want to stay up to date on a daily basis?

Enable the mail alert feature now!