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CVE-2021-21392— Open redirect via transitional IPv6 addresses on dual-stack networks

Quick assessment

Affected
matrix-org synapse
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.

Apache Synapse是美国阿帕奇（Apache）基金会的一款轻量级ESB（企业服务总线）。 Synapse 1.28.0版本之前存在安全漏洞，该漏洞源于当Synapse使用过渡IPv6地址时，对用户提供的域的请求不限于外部IP地址。在计算第三方邀请事件的密钥有效性，发送推送通知以及生成URL预览时，对联合身份验证服务器的出站请求会受到影响。

CVSS 6.3 · Medium EPSS 0.94% · P60

Possible ATT&CK Techniques 1 AI

T1046 · Network Service Discovery
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I. Basic Information for CVE-2021-21392

Vulnerability Information
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Vulnerability Title
Open redirect via transitional IPv6 addresses on dual-stack networks
Source: CVE Program / CVE List V5
Vulnerability Description
Synapse is a Matrix reference homeserver written in python (pypi package matrix-synapse). Matrix is an ecosystem for open federated Instant Messaging and VoIP. In Synapse before version 1.28.0 requests to user provided domains were not restricted to external IP addresses when transitional IPv6 addresses were used. Outbound requests to federation, identity servers, when calculating the key validity for third-party invite events, sending push notifications, and generating URL previews are affected. This could cause Synapse to make requests to internal infrastructure on dual-stack networks. See referenced GitHub security advisory for details and workarounds.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
指向未可信站点的URL重定向(开放重定向)
Source: CVE Program / CVE List V5
Vulnerability Title
Apache Synapse 输入验证错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Apache Synapse是美国阿帕奇（Apache）基金会的一款轻量级ESB（企业服务总线）。 Synapse 1.28.0版本之前存在安全漏洞，该漏洞源于当Synapse使用过渡IPv6地址时，对用户提供的域的请求不限于外部IP地址。在计算第三方邀请事件的密钥有效性，发送推送通知以及生成URL预览时，对联合身份验证服务器的出站请求会受到影响。
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
matrix-org synapse < 1.28.0 -

II. Public POCs for CVE-2021-21392

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III. Intelligence Information for CVE-2021-21392

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Patches & Fixes for CVE-2021-21392 (1)

Vendor Advisories for CVE-2021-21392 (1)

Mailing List Discussions for CVE-2021-21392 (1)

Other References for CVE-2021-21392 (1)

Same Patch Batch · matrix-org · 2021-04-12 · 3 CVEs total

CVE-2021-21393 5.3 MEDIUM Denial of service (via resource exhaustion) due to improper input validation on groups/com
CVE-2021-21394 5.3 MEDIUM Denial of service (via resource exhaustion) due to improper input validation on third-part

IV. Related Vulnerabilities

Same product: synapse
Same vendor: matrix-org
Same weakness: CWE-601

V. Comments for CVE-2021-21392

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