OAuth code theft via redirect allowlist bypass
Published Aug 13, 2026 · Updated Aug 13, 2026
Open redirect in Backstage before 0.29.2 allows remote attackers to capture OAuth authorization codes through crafted redirect URIs. The auth backend matches glob allowlist patterns against whole URL strings, so hostname wildcards cross into paths and admit attacker-controlled hosts. Exploitation requires an experimental feature, a custom wildcard-hostname or protocol-less pattern, and victim completion of the OAuth flow; default configurations are unaffected.
Summary
What happened
Open redirect in Backstage before 0.29.2 allows remote attackers to capture OAuth authorization codes through crafted redirect URIs. The auth backend matches glob allowlist patterns against whole URL strings, so hostname wildcards cross into paths and admit attacker-controlled hosts. Exploitation requires an experimental feature, a custom wildcard-hostname or protocol-less pattern, and victim completion of the OAuth flow; default configurations are unaffected.
The record
- CVE
- CVE-2026-73563
- Published
- Aug 13, 2026
- Updated
- Aug 13, 2026
- Vendor
- Backstage
- Product
- Backstage
- Classifications
- CWE-1289, T1528
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 13, 2026CVE publishedPublication date reported by the CVE source.
- Aug 13, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 0.29.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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