User redirection via unvalidated referer parameter
Published Jul 27, 2023 · Updated Jul 9, 2026
Open redirect in IceWarp MailServer 13.0.1.2 allows remote attackers to redirect users to attacker-controlled sites via a crafted URL. The unauthenticated basic WebClient endpoint accepts an arbitrary referer parameter and returns that external value as the redirect destination without restricting its origin. Exploitation requires a user to follow the crafted IceWarp URL, enabling phishing or navigation to attacker-controlled content.
Summary
What happened
Open redirect in IceWarp MailServer 13.0.1.2 allows remote attackers to redirect users to attacker-controlled sites via a crafted URL. The unauthenticated basic WebClient endpoint accepts an arbitrary referer parameter and returns that external value as the redirect destination without restricting its origin. Exploitation requires a user to follow the crafted IceWarp URL, enabling phishing or navigation to attacker-controlled content.
The record
- CVE
- CVE-2021-36580
- Published
- Jul 27, 2023
- Updated
- Jul 9, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-601, T1204.001
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 27, 2023CVE publishedPublication date reported by the CVE source.
- Jul 9, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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What is affected?
Affected products and versions are unavailable in this record.
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
- Referer-parameter reproduction stepsproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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