Go to homepageCyberStrike

Menu

Star on GitHub · 3.4k
Sign inDownload

CVE-2026-77164

6.2 · MEDIUM

Circles' remote-instance signature verification fetches the attacker-supplied keyId URL before trust in the remote instance is established, and explicitly allows local/private addresses for this re…

Published Sep 18, 2026CWE-918EPSS 0.19%

Overview

CVE-2026-77164 is a medium-severity vulnerability. It was published on September 18, 2026 and has a CVSS 3.0 base score of 6.2 (MEDIUM).

This vulnerability has a CVSS 3.0 base score of 6.2, rated MEDIUM. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.

Technical description

Circles' remote-instance signature verification fetches the attacker-supplied keyId URL before trust in the remote instance is established, and explicitly allows local/private addresses for this request, bypassing Nextcloud's core SSRF protections. The public, unauthenticated endpoints POST /apps/circles/event/ and POST /apps/circles/incoming/ reach this code path, allowing any unauthenticated user to force the server to issue a GET request to an internal address.

The response body of the internal request is never returned to the requester, so this is blind SSRF: an attacker can determine whether an internal service is reachable, but cannot read its response contents through this endpoint alone.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refhackerone.com/reports/3303283

How CyberStrike helps

Frequently asked questions

What is CVE-2026-77164?

CVE-2026-77164 is a medium-severity vulnerability. It was published on September 18, 2026 and has a CVSS 3.0 base score of 6.2 (MEDIUM).

How severe is CVE-2026-77164?

This vulnerability has a CVSS 3.0 base score of 6.2, rated MEDIUM. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-77164?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-77164?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-77164 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

Related MEDIUM CVEs from 2026

View all
Browse by year2026202520242023202220212020201920182017201620152014201320122011201020092008200720062005200420032002200120001999
LiveWatch live →