CVE-2021-42006: An out-of-bounds access in GffLine::GffLine in gff.cpp in GCLib 0.12.7 allows an attacker to cause a segmentat

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HIGH 8.8DOWNGRADE

CVE-2021-42006 is a high-severity flaw (CVSS 8.8) affecting gclib. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An out-of-bounds access in GffLine::GffLine in gff.cpp in GCLib 0.12.7 allows an attacker to cause a segmentation fault or possibly have unspecified other impact via a crafted GFF file.

Why this priority

High severity
Public exploit reference

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	1.1% (top 35%)
CISA exploited list	No
Weakness	CWE-125
Published	2021-10-04
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: gclib project

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

Am I affected?

Timeline

2021-10-04 23:15 UTCPublished CVE record published
2026-06-17 04:09 UTCUpdated Record last modified

gclib project gclib DOWNGRADE

Affected: 0.12.7

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.12.7

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 0.12.7 (Debian / Ubuntu)

apt-cache madison gclib sudo apt install gclib=<VERSION_BEFORE_0.12.7> sudo apt-mark hold gclib

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

dnf --showduplicates list gclib sudo dnf downgrade gclib-<VERSION_BEFORE_0.12.7> sudo dnf versionlock add gclib

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-2021-42006?

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

Is CVE-2021-42006 being exploited?

CVE-2021-42006 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-2021-42006 affect?

CVE-2021-42006 affects gclib. Severity is high (CVSS 8.8). An out-of-bounds access in GffLine::GffLine in gff.cpp in GCLib 0.12.7 allows an attacker to cause a segmentation fault or possibly have unspecified other impact via a crafted GFF file.

How urgent is CVE-2021-42006?

Priority 52/100. High severity; Public exploit reference

References

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