Authorization bypass via signed-URL length extension
Published Jul 9, 2021 · Updated Oct 25, 2024
Improper signature verification in Fortinet FortiMail 6.2.0 through 6.2.7 and 6.4.0 through 6.4.4 allows remote attackers to bypass signed URLs. FortiMail omits a required cryptographic step when hashing signed URLs, allowing appended data to retain an accepted digest through a length-extension attack. No credentials or user interaction are required; the extended URL passes signature verification and bypasses the access control bound to the original URL.
Summary
What happened
Improper signature verification in Fortinet FortiMail 6.2.0 through 6.2.7 and 6.4.0 through 6.4.4 allows remote attackers to bypass signed URLs. FortiMail omits a required cryptographic step when hashing signed URLs, allowing appended data to retain an accepted digest through a length-extension attack. No credentials or user interaction are required; the extended URL passes signature verification and bypasses the access control bound to the original URL.
The record
- CVE
- CVE-2021-24020
- Published
- Jul 9, 2021
- Updated
- Oct 25, 2024
- Vendor
- Fortinet
- Product
- FortiMail
- Classifications
- CWE-347, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 9, 2021CVE publishedPublication date reported by the CVE source.
- Oct 25, 2024Record 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=FortiMail 6.4.0 through 6.4.4, and 6.2.0 through 6.2.7
What conditions does exploitation require?
What is affected?
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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