Open redirect via incomplete leading-slash normalization
Published Feb 25, 2026 · Updated Feb 25, 2026
Open redirect in Angular SSR allows remote attackers to send users to attacker-controlled sites through a crafted X-Forwarded-Prefix header. joinUrlParts removes only the first leading slash, leaving a protocol-relative URL that is written to the redirect Location header. Exposure requires SSR redirect routes, an unsanitized forwarded prefix, and a cache that does not vary on that header; a poisoned response can redirect later visitors.
Summary
What happened
Open redirect in Angular SSR allows remote attackers to send users to attacker-controlled sites through a crafted X-Forwarded-Prefix header. joinUrlParts removes only the first leading slash, leaving a protocol-relative URL that is written to the redirect Location header. Exposure requires SSR redirect routes, an unsanitized forwarded prefix, and a cache that does not vary on that header; a poisoned response can redirect later visitors.
The record
- CVE
- CVE-2026-27738
- Published
- Feb 25, 2026
- Updated
- Feb 25, 2026
- Vendor
- Angular
- Product
- Angular CLI
- Classifications
- CWE-601, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 25, 2026CVE publishedPublication date reported by the CVE source.
- Feb 25, 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=>= 19.0.0-next.0, < 19.2.21
- Affected versionversion=>= 20.0.0-next.0, < 20.3.17
- Affected versionversion=>= 21.0.0-next.0, < 21.1.5
- Affected versionversion=>= 21.2.0-next.2, < 21.2.0-rc.0
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
- Angular SSR X-Forwarded-Prefix minimal reproductionproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
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