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CVE-2026-77164

Quick assessment

Affected
Nextcloud Server
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

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,

AI Predicted 5.3 Difficulty: Easy
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I. Basic Information for CVE-2026-77164

Vulnerability Information

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Vulnerability Title
N/A
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
服务端请求伪造(SSRF)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Nextcloud Server 31.0.0 ~ 32.0.0 -

II. Public POCs for CVE-2026-77164

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III. Intelligence Information for CVE-2026-77164

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Other References for CVE-2026-77164 (1)

Same Patch Batch · Nextcloud · 2026-09-18 · 7 CVEs total

CVE-2026-77169 Nextcloud团队文件夹应用权限绕过漏洞
CVE-2026-77170 Deck配置API越权设置任意看板配置漏洞
CVE-2026-82982 CVE-2026-82982
CVE-2026-82980 CVE-2026-82980
CVE-2026-82985 CVE-2026-82985
CVE-2026-68493 CVE-2026-68493

IV. Related Vulnerabilities

Same product: Server
Same vendor: Nextcloud
Same weakness: CWE-918

V. Comments for CVE-2026-77164

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