CVE-2021-32842: SharpZipLib (or #ziplib) is a Zip, GZip, Tar and BZip2 library

Routine

MEDIUM 4.0UPGRADE

CVE-2021-32842 is a medium-severity flaw (CVSS 4.0) affecting sharpziplib. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

SharpZipLib (or #ziplib) is a Zip, GZip, Tar and BZip2 library. Starting version 1.0.0 and prior to version 1.3.3, a check was added if the destination file is under a destination directory. However, it is not enforced that `_baseDirectory` ends with slash. If the _baseDirectory is not slash terminated like `/home/user/dir` it is possible to create a file with a name thats begins as the destination directory one level up from the directory, i.e.

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	4.0 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.9% (top 41%)
CISA exploited list	No
Weakness	CWE-22
Published	2022-01-26
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: sharpziplib project

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

Am I affected?

Timeline

2022-01-26 21:15 UTCPublished CVE record published
2026-06-17 03:53 UTCUpdated Record last modified

sharpziplib project sharpziplib UPGRADE

Affected: >= 1.0.0 and < 1.3.3

Fixed in: 1.3.3

Safe to downgrade to: a release before 1.0.0

1. Check installed version

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

2. UPGRADE to 1.3.3 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade sharpziplib

Note

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

3. If no update is available yet, DOWNGRADE to a release before 1.0.0 (Debian / Ubuntu)

apt-cache madison sharpziplib sudo apt install sharpziplib=<VERSION_BEFORE_1.0.0> sudo apt-mark hold sharpziplib

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list sharpziplib sudo dnf downgrade sharpziplib-<VERSION_BEFORE_1.0.0> sudo dnf versionlock add sharpziplib

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-2021-32842?

sharpziplib: upgrade to 1.3.3. Exact commands for each OS are on this page.

Is CVE-2021-32842 being exploited?

CVE-2021-32842 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-2021-32842 affect?

CVE-2021-32842 affects sharpziplib. Severity is medium (CVSS 4.0). SharpZipLib (or #ziplib) is a Zip, GZip, Tar and BZip2 library. Starting version 1.0.0 and prior to version 1.3.3, a check was added if the destination file is under a destination directory. However, it is not enforced that `_baseDirectory`

How urgent is CVE-2021-32842?

Priority 34/100. Public exploit reference

Related CVEs

CVE-2021-32841 MEDIUM 4.0 UPGRADE SharpZipLib (or #ziplib) is a Zip, GZip, Tar and BZip2 library
CVE-2021-32840 HIGH 7.3 UPGRADE SharpZipLib (or #ziplib) is a Zip, GZip, Tar and BZip2 library

References

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