Read the docs
TI-2021-05003 Aliases CVE-2021-21958GHSA-5fcw-h565-mjpq

Heap-based buffer overflow in Hancom

Priority HIGH 69CWE-122Published · Updated

Key facts

Attack vector
Local
Privileges required
None
User interaction
Required
Attack complexity
Low
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
No fix listed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-122 and the CVSS impact.

Summary

A heap-based buffer overflow vulnerability exists in the Hword HwordApp.dll functionality of Hancom Office 2020 11.0.0.2353. A specially-crafted malformed file can lead to memory corruption and potential arbitrary code execution. An attacker can provide a malicious file to trigger this vulnerability.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.011 65th percentileScored 2026-11-07
Public exploit Yes 2 exploit referencesTagged by NVD
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
—HancomHancom Office 2020 11.0.0.2353—No fix listedCNA
  • Hancom Vendor— Affected Hancom Office 2020 11.0.0.2353 Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:hancom:hancom_office_2020:11.0.0.2353:*:*:*:*:*:*:*11.0.0.2353VulnerableHancom
  • cpe:2.3:a:hancom:hancom_office_2020:11.0.0.2353:*:*:*:*:*:*:* Versions 11.0.0.2353 Vulnerable ·Hancom

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-21958
  2. 2026-10-03 Alias added: GHSA-5fcw-h565-mjpq

References

Exploit 2

  • TI-2023-15823 Use after free in Hancom Office 2020 CVSS 3.1HIGH 8.8
  • TI-2022-14904 A buffer underflow vulnerability exists in the way Hword of Hancom Office 2020 version… CVSS 3.1HIGH 7.8

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences