Headline
CVE-2021-25636: CVE-2021-25636 | LibreOffice - Free Office Suite - Based on OpenOffice
LibreOffice supports digital signatures of ODF documents and macros within documents, presenting visual aids that no alteration of the document occurred since the last signing and that the signature is valid. An Improper Certificate Validation vulnerability in LibreOffice allowed an attacker to create a digitally signed ODF document, by manipulating the documentsignatures.xml or macrosignatures.xml stream within the document to contain both “X509Data” and “KeyValue” children of the “KeyInfo” tag, which when opened caused LibreOffice to verify using the “KeyValue” but to report verification with the unrelated “X509Data” value. This issue affects: The Document Foundation LibreOffice 7.2 versions prior to 7.2.5.
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CVE-2021-25636
CVE-2021-25636
Title: Incorrect trust validation of signature with ambiguous KeyInfo children
Announced: February 22, 2022
Fixed in: LibreOffice 7.2.5/7.3.0
Description:
LibreOffice supports digital signatures of ODF documents and macros within documents, presenting visual aids that no alteration of the document occurred since the last signing and that the signature is valid.
An Improper Certificate Validation vulnerability in LibreOffice allowed an attacker to create a digitally signed ODF document, by manipulating the documentsignatures.xml or macrosignatures.xml stream within the document to contain both “X509Data” and “KeyValue” children of the “KeyInfo” tag[1], which when opened caused LibreOffice to verify using the “KeyValue” but to report verification with the unrelated “X509Data” value.
In versions >= 7.2.5 (and >= 7.3.0) certificate validation is configured to only consider X509Data children to limit validation to X509 certificates only.
- Thanks to NDS of Ruhr University Bochum for discovering and reporting this problem.
- Thanks to Aleksey Sanin for advice on a solution
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The team behind LibreOffice has released security updates to fix three security flaws in the productivity software, one of which could be exploited to achieve arbitrary code execution on affected systems. Tracked as CVE-2022-26305, the issue has been described as a case of improper certificate validation when checking whether a macro is signed by a trusted author, leading to the execution of