CVE-2021-28856: In Deark before v1.5.8, a specially crafted input file can cause a division by zero in (src/fmtutil.c) because

Q: How do I fix CVE-2021-28856?

deark: upgrade to 1.5.8. Exact commands for each OS are on this page.

Q: Is CVE-2021-28856 being exploited?

CVE-2021-28856 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-28856 affect?

CVE-2021-28856 affects deark. Severity is medium (CVSS 5.5). In Deark before v1.5.8, a specially crafted input file can cause a division by zero in (src/fmtutil.c) because of the value of pixelsize.

Q: How urgent is CVE-2021-28856?

Priority 34/100. No elevated risk signals yet.

Routine

MEDIUM 5.5UPGRADE

CVE-2021-28856 is a medium-severity flaw (CVSS 5.5) affecting deark. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In Deark before v1.5.8, a specially crafted input file can cause a division by zero in (src/fmtutil.c) because of the value of pixelsize.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	5.5 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.8% (top 42%)
CISA exploited list	No
Weakness	CWE-369
Published	2021-04-14
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: entropymine

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

Am I affected?

Timeline

2021-04-14 17:15 UTCPublished CVE record published
2026-06-17 03:46 UTCUpdated Record last modified

entropymine deark UPGRADE

Affected: < 1.5.8

Fixed in: 1.5.8

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 1.5.8 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade deark

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade deark

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

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-2021-28856?

deark: upgrade to 1.5.8. Exact commands for each OS are on this page.

Is CVE-2021-28856 being exploited?

CVE-2021-28856 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-2021-28856 affect?

CVE-2021-28856 affects deark. Severity is medium (CVSS 5.5). In Deark before v1.5.8, a specially crafted input file can cause a division by zero in (src/fmtutil.c) because of the value of pixelsize.

How urgent is CVE-2021-28856?

Priority 34/100. No elevated risk signals yet.

Related CVEs

CVE-2022-43289 HIGH 7.8 DOWNGRADE Deark v.1.6.2 was discovered to contain a stack overflow via the do_prism_read_palette() function at /modules/
CVE-2021-28855 MEDIUM 5.5 UPGRADE In Deark before 1.5.8, a specially crafted input file can cause a NULL pointer dereference in the dbuf_write f

References

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