CVE-2021-27799: ean_leading_zeroes in backend/upcean.c in Zint Barcode Generator 2.9.1 has a stack-based buffer overflow that

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HIGH 7.5REMOTEDOWNGRADE

CVE-2021-27799 is a high-severity flaw (CVSS 7.5) affecting barcode generator. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

ean_leading_zeroes in backend/upcean.c in Zint Barcode Generator 2.9.1 has a stack-based buffer overflow that is reachable from the C API through an application that includes the Zint Barcode Generator library code.

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

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

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.4% (top 16%)
CISA exploited list	No
Weakness	CWE-787
Published	2021-02-26
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: zint

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

Am I affected?

Timeline

2021-02-26 22:15 UTCPublished CVE record published
2026-06-17 03:45 UTCUpdated Record last modified

zint barcode generator DOWNGRADE

Affected: 2.9.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.9.1

1. Check installed version

apt-cache policy barcode-generator || rpm -q barcode-generator || barcode-generator --version

2. No fixed release: DOWNGRADE to a release before 2.9.1 (Debian / Ubuntu)

apt-cache madison barcode-generator sudo apt install barcode-generator=<VERSION_BEFORE_2.9.1> sudo apt-mark hold barcode-generator

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

dnf --showduplicates list barcode-generator sudo dnf downgrade barcode-generator-<VERSION_BEFORE_2.9.1> sudo dnf versionlock add barcode-generator

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-2021-27799?

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

Is CVE-2021-27799 being exploited?

CVE-2021-27799 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-2021-27799 affect?

CVE-2021-27799 affects barcode generator. Severity is high (CVSS 7.5). ean_leading_zeroes in backend/upcean.c in Zint Barcode Generator 2.9.1 has a stack-based buffer overflow that is reachable from the C API through an application that includes the Zint Barcode Generator library code.

How urgent is CVE-2021-27799?

Priority 57/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2021-39247 MEDIUM 6.5 UPGRADE Zint Barcode Generator before 2.10.0 has a one-byte buffer over-read, related to is_last_single_ascii in code1

References

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