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

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HIGH 7.5REMOTEDOWNGRADE

CVE-2017-7523 is a high-severity flaw (CVSS 7.5) affecting cygwin. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Cygwin versions 1.7.2 up to and including 1.8.0 are vulnerable to buffer overflow vulnerability in wcsxfrm/wcsxfrm_l functions resulting into denial-of-service by crashing the process or potential hijack of the process running with administrative privileges triggered by specially crafted input string.

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	2.7% (top 14%)
CISA exploited list	No
Weakness	CWE-787, CWE-119
Published	2017-07-21
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

2017-07-21 22:29 UTCPublished CVE record published
2026-06-17 01:24 UTCUpdated Record last modified

cygwin cygwin DOWNGRADE

Affected: 1.7.2 · 1.7.3 · 1.7.5 · 1.7.6 · 1.7.7 · 1.7.8 · 1.7.9 · 1.7.10

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.7.2

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 1.7.2 (Debian / Ubuntu)

apt-cache madison cygwin sudo apt install cygwin=<VERSION_BEFORE_1.7.2> sudo apt-mark hold cygwin

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

dnf --showduplicates list cygwin sudo dnf downgrade cygwin-<VERSION_BEFORE_1.7.2> sudo dnf versionlock add cygwin

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-2017-7523?

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

Is CVE-2017-7523 being exploited?

CVE-2017-7523 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-2017-7523 affect?

CVE-2017-7523 affects cygwin. Severity is high (CVSS 7.5). Cygwin versions 1.7.2 up to and including 1.8.0 are vulnerable to buffer overflow vulnerability in wcsxfrm/wcsxfrm_l functions resulting into denial-of-service by crashing the process or potential hijack of the process running with administ

How urgent is CVE-2017-7523?

Priority 58/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2016-3067 CRITICAL 9.8 UPGRADE Cygwin before 2.5.0 does not properly handle updating permissions when changing users, which allows attackers

References

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