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Fencer Vulns
high 8.8

CVE-2020-13544 json

An exploitable sign extension vulnerability exists in the TextMaker document parsing functionality of SoftMaker Office 2021’s TextMaker app…

published 2021-01-06 5 y ago modified 2026-06-17 4 mo ago also EUVD-2020-5791

cvss
8.8
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.6%
EPSS 1.6% chance of exploitation in 30 days, percentile 75%
public exploits
0
none known

Summary

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.

Exploit prediction

1.60% chance of exploitation in the next 30 days, higher than 75% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • talosintelligence.com https://talosintelligence.com/vulnerability_reports/TALOS-2020-1161 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.0 8.8 CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD 2.0 6.8 AV:N/AC:M/Au:N/C:P/I:P/A:P

Affected products

  • n/a Softmaker

Classification

Weakness
  • CWE-194 Unexpected Sign Extension
  • CWE-681 Incorrect Conversion between Numeric Types

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.