CVE-2021-26608: An arbitrary file download and execution vulnerability was found in the HShell.dll of handysoft Co., Ltd group

This month

HIGH 8.8DOWNGRADE

CVE-2021-26608 is a high-severity flaw (CVSS 8.8) affecting hshell. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An arbitrary file download and execution vulnerability was found in the HShell.dll of handysoft Co., Ltd groupware ActiveX module. This issue is due to missing support for integrity check of download URL or downloaded file hash.

Why this priority

High severity

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.6% (top 52%)
CISA exploited list	No
Weakness	CWE-353, CWE-345
Published	2021-09-09
Last modified	2026-06-17

Publisher (CNA): KrCERT/CC · Vendor: handysoft

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-09-09 13:15 UTCPublished CVE record published
2026-06-17 03:43 UTCUpdated Record last modified

handysoft hshell DOWNGRADE

Affected: 1.7.4.5 · 2.0.3.5 · 4.0.1.6

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.7.4.5

1. Check installed version

apt-cache policy hshell || rpm -q hshell || hshell --version

2. No fixed release: DOWNGRADE to a release before 1.7.4.5 (Debian / Ubuntu)

apt-cache madison hshell sudo apt install hshell=<VERSION_BEFORE_1.7.4.5> sudo apt-mark hold hshell

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list hshell sudo dnf downgrade hshell-<VERSION_BEFORE_1.7.4.5> sudo dnf versionlock add hshell

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-26608?

hshell: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-26608 being exploited?

CVE-2021-26608 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-26608 affect?

CVE-2021-26608 affects hshell. Severity is high (CVSS 8.8). An arbitrary file download and execution vulnerability was found in the HShell.dll of handysoft Co., Ltd groupware ActiveX module. This issue is due to missing support for integrity check of download URL or downloaded file hash.

How urgent is CVE-2021-26608?

Priority 43/100. High severity

References

← Back to latest CVEs