SSRF via filter bypass due to lax checking on IPs

Description

Impact

Attackers can leverage enclosed alphanumeric payloads to bypass IP filters and gain SSRF. An example can be using ⑯⑨。②⑤④。⑯⑨｡②⑤④ which would allow an attacker to read crucial metadata if the server is hosted on the AWS platform. The above payload will resolve to the magic IP of AWS namely 169.254.169.254 but bypasses all the filtering present in the code itself.

Patches

It is recommended that the Nextcloud Server is upgraded to 24.0.8 or 23.0.12
It is recommended that the Nextcloud Enterprise Server is upgraded to 24.0.8 or 23.0.12

Workarounds

No workaround available

References

• HackerOne
• PullRequest

For more information

If you have any questions or comments about this advisory:

• Create a post in nextcloud/security-advisories
• Customers: Open a support ticket at support.nextcloud.com