CVE-2019-7639: An issue was discovered in gsi-openssh-server 7.9p1 on Fedora 29

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HIGH 8.1REMOTEWATCHLISTMITIGATEDOWNGRADE

CVE-2019-7639 is a high-severity flaw (CVSS 8.1) affecting fedora, gsi-openssh. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue was discovered in gsi-openssh-server 7.9p1 on Fedora 29. If PermitPAMUserChange is set to yes in the /etc/gsissh/sshd_config file, logins succeed with a valid username and an incorrect password, even though a failure entry is recorded in the /var/log/messages file.

Why this priority

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

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

Risk facts

CVSS score	8.1 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	1.2% (top 32%)
CISA exploited list	No
Weakness	CWE-863
Published	2019-02-08
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: fedoraproject · gsi-openssh project

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

Am I affected?

Timeline

2019-02-08 11:29 UTCPublished CVE record published
2026-06-17 02:40 UTCUpdated Record last modified

fedoraproject fedora MITIGATE

Affected: 28 · 29

Fixed in: no fixed release known

Safe to downgrade to: a release before 28

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

gsi-openssh project gsi-openssh DOWNGRADE

Affected: 7.9 p1

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.9

1. Check installed version

apt-cache policy gsi-openssh || rpm -q gsi-openssh || gsi-openssh --version

2. No fixed release: DOWNGRADE to a release before 7.9 (Debian / Ubuntu)

apt-cache madison gsi-openssh sudo apt install gsi-openssh=<VERSION_BEFORE_7.9> sudo apt-mark hold gsi-openssh

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

dnf --showduplicates list gsi-openssh sudo dnf downgrade gsi-openssh-<VERSION_BEFORE_7.9> sudo dnf versionlock add gsi-openssh

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-2019-7639?

fedora: mitigate or apply the listed mitigation; gsi-openssh: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2019-7639 being exploited?

CVE-2019-7639 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-2019-7639 affect?

CVE-2019-7639 affects fedora, gsi-openssh. Severity is high (CVSS 8.1). An issue was discovered in gsi-openssh-server 7.9p1 on Fedora 29. If PermitPAMUserChange is set to yes in the /etc/gsissh/sshd_config file, logins succeed with a valid username and an incorrect password, even though a failure entry is recor

How urgent is CVE-2019-7639?

Priority 60/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

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References

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