Session-cookie theft via unvalidated SAML redirect
Published Sep 15, 2025 · Updated Sep 15, 2025
Open redirect in Mattermost 10.5.0 through 10.5.9, 10.9.0 through 10.9.4, and 10.10.0 through 10.10.1 lets attackers steal cookies. The fullyQualifiedRedirectURL helper concatenates a relative redirect_to value with the site URL without normalizing and constraining the resulting path. An attacker must supply a malicious link and the user must complete SAML authentication; the ensuing redirect can send session cookies to an attacker-controlled URL, enabling session hijacking.
Summary
What happened
Open redirect in Mattermost 10.5.0 through 10.5.9, 10.9.0 through 10.9.4, and 10.10.0 through 10.10.1 lets attackers steal cookies. The fullyQualifiedRedirectURL helper concatenates a relative redirect_to value with the site URL without normalizing and constraining the resulting path. An attacker must supply a malicious link and the user must complete SAML authentication; the ensuing redirect can send session cookies to an attacker-controlled URL, enabling session hijacking.
The record
- CVE
- CVE-2025-9072
- Published
- Sep 15, 2025
- Updated
- Sep 15, 2025
- Vendor
- Mattermost
- Product
- Mattermost
- Classifications
- CWE-601, T1539
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Sep 15, 2025CVE publishedPublication date reported by the CVE source.
- Sep 15, 2025Record 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=10.10.0 <=10.10.1
- Affected versionversion=10.5.0 <=10.5.9
- Affected versionversion=10.9.0 <=10.9.4
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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