CVE-2019-9853: Insufficient URL decoding flaw in categorizing macro location

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 3.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2019-09-27 · updated 2026-06-17
Weakness: CWE-116

Description

LibreOffice documents can contain macros. The execution of those macros is controlled by the document security settings, typically execution of macros are blocked by default. A URL decoding flaw existed in how the urls to the macros within the document were processed and categorized, resulting in the possibility to construct a document where macro execution bypassed the security settings. The documents were correctly detected as containing macros, and prompted the user to their existence within the documents, but macros within the document were subsequently not controlled by the security settings allowing arbitrary macro execution This issue affects: LibreOffice 6.2 series versions prior to 6.2.7; LibreOffice 6.3 series versions prior to 6.3.1.

Affected products

The Document Foundation LibreOffice: from 6.2.0 before 6.2.6; from 6.3.0 before 6.3.1 — fixed in 6.2.6, 6.3.1

How to fix

Upgrade to a fixed version: The Document Foundation LibreOffice 6.2.6, 6.3.1. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2019-9853 or the next vulnerability affects your stack