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CVE-2026-91973— Vikunja before 2.6.0 Authentication Bypass via CalDAV BasicAuth

Quick assessment

Affected
go-vikunja vikunja
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.

Vikunja 2.6.0 之前版本在 CalDAV BasicAuth 端点中存在认证绕过漏洞，且这些端点缺乏速率限制保护。未经身份验证的远程攻击者可以对 /dav、/.well-known 和 /feeds 路由发起无限次的凭证猜测请求，从而绕过实例的防暴力破解控制，进而攻破仅依赖密码的账户。

CVSS 7.5 · High
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I. Basic Information for CVE-2026-91973

Vulnerability Information
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Vulnerability Title
Vikunja before 2.6.0 Authentication Bypass via CalDAV BasicAuth
Source: CVE Program / CVE List V5
Vulnerability Description
Vikunja before 2.6.0 contains an authentication bypass vulnerability in CalDAV BasicAuth endpoints that lack rate limiting protection. Remote unauthenticated attackers can issue unbounded credential-guessing requests against /dav, /.well-known, and /feeds routes to bypass the instance's anti-brute-force controls and compromise password-only accounts.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
过多认证尝试的限制不恰当
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
go-vikunja vikunja 0 ~ 2.6.0 -

II. Public POCs for CVE-2026-91973

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III. Intelligence Information for CVE-2026-91973

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Vendor Advisories for CVE-2026-91973 (2)

Same Patch Batch · go-vikunja · 2026-09-15 · 13 CVEs total

CVE-2026-91972 7.5 HIGH Vikunja before 2.6.0 Authentication Bypass via Unthrottled API
CVE-2026-91985 7.5 HIGH Vikunja before 2.6.0 Privilege Escalation via Link Share Hash
CVE-2026-91968 6.5 MEDIUM vikunja before 2.6.0 Denial of Service via unbounded filter recursion
CVE-2026-91971 6.5 MEDIUM Vikunja before 2.6.0 Denial of Service via Avatar Upload
CVE-2026-91979 6.5 MEDIUM Vikunja before 2.6.0 Denial of Service via Decompression Bomb
CVE-2026-91970 6.5 MEDIUM Vikunja before 2.6.0 Resource Exhaustion via Planka Migration
CVE-2026-91969 6.5 MEDIUM vikunja before 2.6.0 Resource Exhaustion via CSV Migration
CVE-2026-91982 4.3 MEDIUM Vikunja before 2.6.0 TOTP Secret Disclosure via API
CVE-2026-91980 4.3 MEDIUM vikunja before 2.6.0 Team Enumeration via Project Share
CVE-2026-91981 4.3 MEDIUM Vikunja before 2.6.0 User Enumeration via v2 API
CVE-2026-91983 4.3 MEDIUM Vikunja before 2.6.0 API Token Scope Bypass via expand Parameter
CVE-2026-91984 4.3 MEDIUM Vikunja before 2.6.0 Broken Object-Level Authorization via task-position

IV. Related Vulnerabilities

Same product: vikunja
Same vendor: go-vikunja
Same weakness: CWE-307

V. Comments for CVE-2026-91973

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