CVE-2021-37704: PhpFastCache is a high-performance backend cache system (packagist package phpfastcache/phpfastcache)

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MEDIUM 5.4UPGRADE

CVE-2021-37704 is a medium-severity flaw (CVSS 5.4) affecting phpfastcache. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

PhpFastCache is a high-performance backend cache system (packagist package phpfastcache/phpfastcache). In versions before 6.1.5, 7.1.2, and 8.0.7 the `phpinfo()` can be exposed if the `/vendor` is not protected from public access. This is a rare situation today since the vendor directory is often located outside the web directory or protected via server rule (.htaccess, etc). Only the v6, v7 and v8 will be patched respectively in 8.0.7, 7.1.2, 6.

Why this priority

EPSS top 7%: very likely to be exploited
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	5.4 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	5.9% (top 7%)
CISA exploited list	No
Weakness	CWE-200, CWE-668
Published	2021-08-12
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: phpfastcache

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

Am I affected?

Timeline

2021-08-12 20:15 UTCPublished CVE record published
2026-06-17 04:01 UTCUpdated Record last modified

phpfastcache phpfastcache UPGRADE

Affected: < 6.1.5 · >= 7.0.0 and < 7.1.2 · >= 8.0.0 and < 8.0.7

Fixed in: 6.1.5, 7.1.2, 8.0.7

Safe to downgrade to: a release before 7.0.0

1. Check installed version

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

2. UPGRADE to 6.1.5 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade phpfastcache

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 7.0.0 (Debian / Ubuntu)

apt-cache madison phpfastcache sudo apt install phpfastcache=<VERSION_BEFORE_7.0.0> sudo apt-mark hold phpfastcache

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

dnf --showduplicates list phpfastcache sudo dnf downgrade phpfastcache-<VERSION_BEFORE_7.0.0> sudo dnf versionlock add phpfastcache

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.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Nuclei scan template: phpfastcache - phpinfo Resource Exposure

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-2021-37704?

phpfastcache: upgrade to 6.1.5, 7.1.2, 8.0.7. Exact commands for each OS are on this page.

Is CVE-2021-37704 being exploited?

CVE-2021-37704 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-2021-37704 affect?

CVE-2021-37704 affects phpfastcache. Severity is medium (CVSS 5.4). PhpFastCache is a high-performance backend cache system (packagist package phpfastcache/phpfastcache). In versions before 6.1.5, 7.1.2, and 8.0.7 the `phpinfo()` can be exposed if the `/vendor` is not protected from public access. This is a

How urgent is CVE-2021-37704?

Priority 47/100. EPSS top 7%: very likely to be exploited; Public exploit reference

References

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