Authentication Bypass in OpenSignLabs OpenSignServer Affects File Access Security

CVE-2026-72691

What is CVE-2026-72691?

OpenSignLabs OpenSignServer version 2.37.0 contains an authentication bypass vulnerability that allows an unauthenticated remote attacker to circumvent security measures. By leveraging the getsignedurl Parse cloud function, attackers can create MASTER_KEY-signed file access tokens for any stored files. The vulnerability arises from a flawed check within the function, which neglects the authentication requirement whenever a docId parameter is provided, enabling malicious actors to forge access tokens by using arbitrary strings as docIds, regardless of the actual presence of the document.

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