An exploitable sign extension vulnerability exists in the TextMaker document parsing functionality of SoftMaker Office 2021’s TextMaker application. A specially crafted document can cause the document parser to sign-extend a length used to terminate a loop, which can later result in the loop’s index being used to write outside the bounds of a heap buffer during the reading of file data. An attacker can entice the victim to open a document to trigger this vulnerability.

References

• https://nvd.nist.gov/vuln/detail/CVE-2020-13544
• https://talosintelligence.com/vulnerability_reports/TALOS-2020-1161