Unauthenticated throttling bypass via forward proxy-chain traversal
Published Dec 22, 2023 · Updated Aug 27, 2024
CWE-307 in Nextcloud Server before 26.0.9 and 27.1.4 allows remote attackers to exceed authentication-attempt limits via proxy headers. Request::getRemoteAddress walks configured forwarded-header names and comma-separated X-Forwarded-For addresses from left to right, so it accepts an attacker-supplied address before the nearest untrusted hop. The bypass requires a trusted reverse proxy and lets unauthenticated requests rotate the apparent client address, weakening IP-based throttling without directly authenticating an account.
Summary
What happened
CWE-307 in Nextcloud Server before 26.0.9 and 27.1.4 allows remote attackers to exceed authentication-attempt limits via proxy headers. Request::getRemoteAddress walks configured forwarded-header names and comma-separated X-Forwarded-For addresses from left to right, so it accepts an attacker-supplied address before the nearest untrusted hop. The bypass requires a trusted reverse proxy and lets unauthenticated requests rotate the apparent client address, weakening IP-based throttling without directly authenticating an account.
The record
- CVE
- CVE-2023-49792
- Published
- Dec 22, 2023
- Updated
- Aug 27, 2024
- Vendor
- Nextcloud GmbH
- Product
- Security Advisories
- Classifications
- CWE-307, T1110
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Dec 22, 2023CVE publishedPublication date reported by the CVE source.
- Aug 27, 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=>= 23.0.0, < 23.0.12.13
- Affected versionversion=>= 24.0.0, < 24.0.12.9
- Affected versionversion=>= 25.0.0, < 25.0.13.4
- Affected versionversion=>= 26.0.0, < 26.0.9
- Affected versionversion=>= 27.0.0, < 27.1.4
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
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Technologies
Your stack
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Your stack
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