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CVE-2021-43825— Use-after-free in Envoy

Quick assessment

Affected
envoyproxy envoy
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Envoy是一款开源的分布式代理服务器。 Envoy 存在资源管理错误漏洞，该漏洞源于Envoy跟踪缓冲的请求和响应数据的数量，如果缓冲数据的数量超过限制，就发送413或500个响应，从而中止请求。然而当缓冲区溢出时，响应由过滤器链处理，操作可能不会正确中止，并导致访问一个释放的内存块。攻击者可利用该漏洞导致拒绝服务。

CVSS 6.1 · Medium EPSS 0.88% · P58

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service
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I. Basic Information for CVE-2021-43825

Vulnerability Information
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Vulnerability Title
Use-after-free in Envoy
Source: CVE Program / CVE List V5
Vulnerability Description
Envoy is an open source edge and service proxy, designed for cloud-native applications. Sending a locally generated response must stop further processing of request or response data. Envoy tracks the amount of buffered request and response data and aborts the request if the amount of buffered data is over the limit by sending 413 or 500 responses. However when the buffer overflows while response is processed by the filter chain the operation may not be aborted correctly and result in accessing a freed memory block. If this happens Envoy will crash resulting in a denial of service.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
释放后使用
Source: CVE Program / CVE List V5
Vulnerability Title
Envoy 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Envoy是一款开源的分布式代理服务器。 Envoy 存在资源管理错误漏洞，该漏洞源于Envoy跟踪缓冲的请求和响应数据的数量，如果缓冲数据的数量超过限制，就发送413或500个响应，从而中止请求。然而当缓冲区溢出时，响应由过滤器链处理，操作可能不会正确中止，并导致访问一个释放的内存块。攻击者可利用该漏洞导致拒绝服务。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
envoyproxy envoy < 1.18.6 -

II. Public POCs for CVE-2021-43825

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III. Intelligence Information for CVE-2021-43825

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Patches & Fixes for CVE-2021-43825 (1)

Vendor Advisories for CVE-2021-43825 (1)

Same Patch Batch · envoyproxy · 2022-02-22 · 8 CVEs total

CVE-2021-43826 7.5 HIGH Crash when tunneling TCP over HTTP in Envoy
CVE-2022-21655 7.5 HIGH Incorrect handling of internal redirects results in crash in Envoy
CVE-2021-43824 7.5 HIGH Null pointer dereference in envoy
CVE-2022-21654 7.4 HIGH Incorrect configuration handling allows TLS session re-use without re-validation in Envoy
CVE-2022-21656 7.4 HIGH X.509 subjectAltName matching bypass in Envoy
CVE-2022-21657 6.8 MEDIUM X.509 Extended Key Usage and Trust Purposes bypass in Envoy
CVE-2022-23606 4.4 MEDIUM Crash when a cluster is deleted in Envoy

IV. Related Vulnerabilities

Same product: envoy
Same vendor: envoyproxy
Same weakness: CWE-416

V. Comments for CVE-2021-43825

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