CVE-2016-3067: Cygwin before 2.5.0 does not properly handle updating permissions when changing users, which allows attackers

Q: How do I fix CVE-2016-3067?

cygwin: upgrade to newer than 2.4.1-1. Exact commands for each OS are on this page.

Q: Is CVE-2016-3067 being exploited?

CVE-2016-3067 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-2016-3067 affect?

CVE-2016-3067 affects cygwin. Severity is critical (CVSS 9.8). Cygwin before 2.5.0 does not properly handle updating permissions when changing users, which allows attackers to gain privileges.

Q: How urgent is CVE-2016-3067?

Priority 60/100. Critical severity; Remotely exploitable, no login, no user action

This week

CRITICAL 9.8REMOTEUPGRADE

CVE-2016-3067 is a critical-severity flaw (CVSS 9.8) affecting cygwin. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Cygwin before 2.5.0 does not properly handle updating permissions when changing users, which allows attackers to gain privileges.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.0% (top 19%)
CISA exploited list	No
Weakness	CWE-264
Published	2017-04-21
Last modified	2026-06-17

Publisher (CNA): Red Hat, Inc. · Vendor: cygwin

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

Am I affected?

Timeline

2017-04-21 20:59 UTCPublished CVE record published
2026-06-17 00:44 UTCUpdated Record last modified

cygwin cygwin UPGRADE

Affected: <= 2.4.1-1

Fixed in: newer than 2.4.1-1

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to newer than 2.4.1-1 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade cygwin

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-2016-3067?

cygwin: upgrade to newer than 2.4.1-1. Exact commands for each OS are on this page.

Is CVE-2016-3067 being exploited?

CVE-2016-3067 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-2016-3067 affect?

CVE-2016-3067 affects cygwin. Severity is critical (CVSS 9.8). Cygwin before 2.5.0 does not properly handle updating permissions when changing users, which allows attackers to gain privileges.

How urgent is CVE-2016-3067?

Priority 60/100. Critical severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2017-7523 HIGH 7.5 DOWNGRADE Cygwin versions 1.7.2 up to and including 1.8.0 are vulnerable to buffer overflow vulnerability in wcsxfrm/wcs

References

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