CVE-2026-6040: CWE-416 Use After Free in The Document Foundation LibreOffice
A heap use-after-free existed when importing the blank-width characters of an ODF number format. A position value read from the document was not checked against the length of the format-code string, so a malformed number format could be processed against memory outside that string. In fixed versions the position is bounds-checked before use.
AI Analysis
Technical Summary
This vulnerability (CVE-2026-6040) in LibreOffice involves a heap use-after-free condition triggered when importing blank-width characters of an ODF number format. The root cause is the lack of bounds checking on a position value read from the document against the length of the format-code string. This allows malformed number formats to cause memory access outside the intended buffer. The issue is classified under CWE-416 (Use After Free) and CWE-787 (Out-of-bounds Write). The vulnerability affects LibreOffice versions 25.8 and 26.2. The vendor has fixed the issue by adding bounds checking on the position value before use.
Potential Impact
Successful exploitation could lead to memory corruption due to use-after-free, potentially causing application crashes or other undefined behavior. The CVSS 4.0 base score is 5.4 (medium severity), indicating limited attack vector (local), low complexity, no privileges required, but requires user interaction. There are no known exploits in the wild at this time.
Mitigation Recommendations
No official patch or remediation level is explicitly stated in the available data. However, the vulnerability description notes that fixed versions include bounds checking on the position value. Users should upgrade to versions later than 25.8 and 26.2 where this fix is applied. Patch status is not yet confirmed — check The Document Foundation's advisory for current remediation guidance.
CVE-2026-6040: CWE-416 Use After Free in The Document Foundation LibreOffice
Description
A heap use-after-free existed when importing the blank-width characters of an ODF number format. A position value read from the document was not checked against the length of the format-code string, so a malformed number format could be processed against memory outside that string. In fixed versions the position is bounds-checked before use.
CVSS v4.0
Score 5.4medium
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability (CVE-2026-6040) in LibreOffice involves a heap use-after-free condition triggered when importing blank-width characters of an ODF number format. The root cause is the lack of bounds checking on a position value read from the document against the length of the format-code string. This allows malformed number formats to cause memory access outside the intended buffer. The issue is classified under CWE-416 (Use After Free) and CWE-787 (Out-of-bounds Write). The vulnerability affects LibreOffice versions 25.8 and 26.2. The vendor has fixed the issue by adding bounds checking on the position value before use.
Potential Impact
Successful exploitation could lead to memory corruption due to use-after-free, potentially causing application crashes or other undefined behavior. The CVSS 4.0 base score is 5.4 (medium severity), indicating limited attack vector (local), low complexity, no privileges required, but requires user interaction. There are no known exploits in the wild at this time.
Mitigation Recommendations
No official patch or remediation level is explicitly stated in the available data. However, the vulnerability description notes that fixed versions include bounds checking on the position value. Users should upgrade to versions later than 25.8 and 26.2 where this fix is applied. Patch status is not yet confirmed — check The Document Foundation's advisory for current remediation guidance.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- Document Fdn.
- Date Reserved
- 2026-04-09T16:42:11.799Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a303db60b89be6888695b1c
Added to database: 6/15/2026, 6:00:22 PM
Last enriched: 6/15/2026, 6:15:33 PM
Last updated: 6/15/2026, 8:19:01 PM
Views: 2
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