CVE-2016-9856: An XSS issue was discovered in phpMyAdmin because of an improper fix for CVE-2016-2559 in PMASA-2016-10

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MEDIUM 6.1DOWNGRADE

CVE-2016-9856 is a medium-severity flaw (CVSS 6.1) affecting phpmyadmin. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An XSS issue was discovered in phpMyAdmin because of an improper fix for CVE-2016-2559 in PMASA-2016-10. This issue is resolved by using a copy of a hash to avoid a race condition. All 4.6.x versions (prior to 4.6.5), 4.4.x versions (prior to 4.4.15.9), and 4.0.x versions (prior to 4.0.10.18) are affected.

Why this priority

No elevated risk signals yet

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

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	1.5% (top 26%)
CISA exploited list	No
Weakness	CWE-79
Published	2016-12-11
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: phpmyadmin

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

Am I affected?

Timeline

2016-12-11 02:59 UTCPublished CVE record published
2026-06-17 00:56 UTCUpdated Record last modified

phpmyadmin phpmyadmin DOWNGRADE

Affected: 4.0.0 · 4.0.1 · 4.0.2 · 4.0.3 · 4.0.4 · 4.0.4.1 · 4.0.4.2 · 4.0.5

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.0.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 4.0.0 (Debian / Ubuntu)

apt-cache madison phpmyadmin sudo apt install phpmyadmin=<VERSION_BEFORE_4.0.0> sudo apt-mark hold phpmyadmin

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

dnf --showduplicates list phpmyadmin sudo dnf downgrade phpmyadmin-<VERSION_BEFORE_4.0.0> sudo dnf versionlock add phpmyadmin

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-2016-9856?

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

Is CVE-2016-9856 being exploited?

CVE-2016-9856 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-2016-9856 affect?

CVE-2016-9856 affects phpmyadmin. Severity is medium (CVSS 6.1). An XSS issue was discovered in phpMyAdmin because of an improper fix for CVE-2016-2559 in PMASA-2016-10. This issue is resolved by using a copy of a hash to avoid a race condition. All 4.6.x versions (prior to 4.6.5), 4.4.x versions (prior

How urgent is CVE-2016-9856?

Priority 40/100. No elevated risk signals yet.

Software pages

phpMyAdmin vulnerabilities

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References

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