What’s Vulnerable › Vulnerabilities

CVE-2023-45660: Require strict cookies for image proxy requests in Nextcloud Mail

• Severity: medium (CVSS 4.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2023-10-16 · updated 2026-06-17
• Weakness: CWE-918

Description

Nextcloud mail is an email app for the Nextcloud home server platform. In affected versions a missing check of origin, target and cookies allows for an attacker to abuse the proxy endpoint to denial of service a third server. It is recommended that the Nextcloud Mail is upgraded to 2.2.8 or 3.3.0. There are no known workarounds for this vulnerability.

Affected products

• nextcloud Mail: from 2.2.0 before 2.2.8; from 3.0.0 before 3.3.0 — fixed in 2.2.8, 3.3.0

How to fix

Upgrade to a fixed version: nextcloud Mail 2.2.8, 3.3.0. Check the vendor advisory for mitigations.

References

• https://github.com/nextcloud/mail/pull/8459
• https://github.com/nextcloud/security-advisories/security/advisories/GHSA-8j9x-fmww-qr37
• https://hackerone.com/reports/1895874
• https://github.com/nextcloud/mail/pull/8459
• https://github.com/nextcloud/security-advisories/security/advisories/GHSA-8j9x-fmww-qr37
• https://hackerone.com/reports/1895874

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