Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1359 CNY

100%
Buy Us a Coffee

CVE-2026-73563— Backstage: Unauthenticated OAuth account takeover via `redirect_uri` allowlist bypass in `@backstage/plugin-auth-backend`

Quick assessment

Affected
backstage backstage
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.

Backstage 是一个用于构建开发者门户的开放框架。在 0.29.2 版本之前，@backstage/plugin-auth-backend 中实验性的动态客户端注册（dynamic client registration）和客户端 ID 元数据文档功能，在匹配 以及 和 选项时，使用了基于完整字符串匹配的 glob 通配符匹配（isMatch glob matching）。 这种机制存在以下安全问题： 1. 主机名通配符可跨越 URL 组件边界进行匹配：攻击者可以构造一个受其控制的重定向 URI，该 URI

CVSS 4.7 · Medium EPSS 0.28% · P19

Affected Version Matrix 1

VendorProduct Version RangeStatus
backstage backstage < 0.29.2 affected
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2026-73563

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
Backstage: Unauthenticated OAuth account takeover via `redirect_uri` allowlist bypass in `@backstage/plugin-auth-backend`
Source: CVE Program / CVE List V5
Vulnerability Description
Backstage is an open framework for building developer portals. Prior to 0.29.2, the experimental dynamic client registration and client ID metadata document features in the @backstage/plugin-auth-backend use full-string matcher.isMatch glob matching for auth.experimentalDynamicClientRegistration.allowedRedirectUriPatterns and the auth.experimentalClientIdMetadataDocuments allowedClientIdPatterns and allowedRedirectUriPatterns options. A hostname wildcard can match across URL component boundaries, allowing an attacker-controlled redirect URI with a trusted hostname suffix in its path to pass the allowlist and receive an OAuth authorization code after a victim completes the flow. Patterns without an explicit protocol can match unintended protocols, and redirect URIs containing embedded credentials are accepted after user information is stripped for matching. The features are experimental and disabled by default; only deployments that enable them and configure custom wildcard-hostname or protocol-less patterns are affected. This issue is first fixed in prerelease version 0.29.2.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/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

Affected Products

Vendor Product Affected Versions CPE Subscribe
backstage backstage < 0.29.2 -

II. Public POCs for CVE-2026-73563

# POC Description Source Link Shenlong Link
AI-Generated POC Premium

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2026-73563

请登录查看更多情报信息。

Vendor Advisories for CVE-2026-73563 (1)

IV. Related Vulnerabilities

Same product: backstage
Same vendor: backstage
Same weakness: CWE-601

V. Comments for CVE-2026-73563

No comments yet

Leave a comment