CVE-2021-32744: Unauthenticated attacker could gain access to currently open files

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-07-21 · updated 2026-06-17
Weakness: CWE-639

Description

Collabora Online is a collaborative online office suite. In versions prior to 4.2.17-1 and version 6.4.9-5, unauthenticated attackers are able to gain access to files which are currently opened by other users in the Collabora Online editor. For successful exploitation the attacker is required to guess the file identifier - the predictability of this file identifier is dependent on external file-storage implementations (this is a potential "IDOR" - Insecure Direct Object Reference - vulnerability). Versions 4.2.17-1 and 6.4.9-5 contain patches for this issue. There is no known workaround except updating the Collabora Online application to one of the patched releases.

Affected products

CollaboraOnline online: before 4.2.17-1; from 6.4.0 before 6.4.9-5 — fixed in 4.2.17-1, 6.4.9-5

How to fix

Upgrade to a fixed version: CollaboraOnline online 4.2.17-1, 6.4.9-5. Check the vendor advisory for mitigations.

References

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