Kanboard is Vulnerable to Reverse Proxy Authentication Bypass
翻译中…平台
php
组件
kanboard
修复版本
1.2.50
CVE-2026-21881 is a critical authentication bypass vulnerability affecting Kanboard project management software versions 1.2.48 and earlier. An attacker can exploit this flaw to impersonate any user, including administrators, gaining unauthorized access to sensitive project data and control over the system. The vulnerability is caused by the application's failure to properly validate HTTP headers when REVERSEPROXYAUTH is enabled. A fix is available in version 1.2.49.
影响与攻击场景翻译中…
This authentication bypass vulnerability poses a significant risk to Kanboard deployments. An attacker can leverage it to gain complete control over the system by impersonating an administrator. This could lead to unauthorized modification or deletion of project data, creation of fake users, and potentially even the installation of malicious code. The blast radius extends to all data managed within the Kanboard instance, and the attacker could use this access to pivot to other systems on the network if Kanboard is integrated with other services. The ease of exploitation, requiring only the ability to craft HTTP headers, makes this a high-priority concern.
利用背景翻译中…
CVE-2026-21881 was publicly disclosed on 2026-01-08. No public proof-of-concept (PoC) code has been released at the time of writing, but the vulnerability's simplicity suggests that a PoC is likely to emerge quickly. The CVSS score of 9.1 (CRITICAL) reflects the high likelihood of exploitation and the significant impact. It is not currently listed on CISA KEV, but its severity warrants monitoring. Active exploitation is not yet confirmed.
哪些人处于风险中翻译中…
Organizations using Kanboard for project management, particularly those with REVERSEPROXYAUTH enabled, are at risk. This includes teams relying on Kanboard for task tracking, bug reporting, and collaboration. Shared hosting environments where Kanboard is installed alongside other applications are also at increased risk due to the potential for cross-site contamination.
检测步骤翻译中…
• php: Examine Kanboard configuration files for the presence and value of REVERSEPROXYAUTH. Check access logs for unusual authentication attempts with spoofed HTTP headers.
• generic web: Use curl to test authentication with crafted HTTP headers. Example:
curl -H "X-Kanboard-User: attacker" http://kanboard.example.com/login• generic web: Monitor web server access logs for requests containing suspicious or unexpected values in HTTP headers related to authentication (e.g., X-Kanboard-User).
攻击时间线
- Disclosure
disclosure
威胁情报
漏洞利用状态
EPSS
0.32% (55% 百分位)
CISA SSVC
CVSS 向量
这些指标意味着什么？
- Attack Vector
- 网络 — 可通过互联网远程利用，无需物理或本地访问。攻击面最大。
- Attack Complexity
- 低 — 无需特殊条件，可以稳定地利用漏洞。
- Privileges Required
- 无 — 无需认证，无需凭证即可利用。
- User Interaction
- 无 — 攻击自动且无声，受害者无需任何操作。
- Scope
- 未改变 — 影响仅限于脆弱组件本身。
- Confidentiality
- 高 — 完全丧失机密性，攻击者可读取所有数据。
- Integrity
- 高 — 攻击者可写入、修改或删除任何数据。
- Availability
- 无 — 无可用性影响。
受影响的软件
弱点分类 (CWE)
时间线
- 已保留
- 发布日期
- EPSS 更新日期
缓解措施和替代方案翻译中…
The primary mitigation for CVE-2026-21881 is to immediately upgrade Kanboard to version 1.2.49 or later. If upgrading is not immediately feasible, disabling the REVERSEPROXYAUTH feature can reduce the attack surface, but this may impact legitimate users relying on reverse proxy authentication. Consider implementing a Web Application Firewall (WAF) with rules to filter suspicious HTTP headers, specifically those related to user authentication. Regularly review Kanboard's access logs for any unusual activity. After upgrading, confirm the fix by attempting to authenticate with a spoofed HTTP header; authentication should fail.
修复方法翻译中…
Actualice Kanboard a la versión 1.2.49 o superior. Esta versión corrige la vulnerabilidad de omisión de autenticación al validar correctamente el origen de las cabeceras HTTP cuando REVERSE_PROXY_AUTH está habilitado. La actualización previene la suplantación de usuarios, incluyendo administradores.
CVE 安全通讯
漏洞分析和关键警报直接发送到您的邮箱。
常见问题翻译中…
What is CVE-2026-21881 — Authentication Bypass in Kanboard?
CVE-2026-21881 is a critical vulnerability in Kanboard versions 1.2.48 and below that allows attackers to bypass authentication by spoofing HTTP headers, potentially impersonating administrators.
Am I affected by CVE-2026-21881 in Kanboard?
You are affected if you are using Kanboard version 1.2.48 or earlier and have REVERSEPROXYAUTH enabled. Upgrade to version 1.2.49 to mitigate the risk.
How do I fix CVE-2026-21881 in Kanboard?
The recommended fix is to upgrade Kanboard to version 1.2.49 or later. If upgrading is not possible, disable REVERSEPROXYAUTH as a temporary workaround.
Is CVE-2026-21881 being actively exploited?
Active exploitation has not been confirmed at this time, but the vulnerability's simplicity suggests it may be exploited soon.
Where can I find the official Kanboard advisory for CVE-2026-21881?
Refer to the Kanboard security advisory for detailed information and updates: [https://kanboard.org/security/advisories](https://kanboard.org/security/advisories)