CVE-2021-27677: Cross-site scripting (XSS) vulnerability in Galleries in Batflat CMS 1.3.6 allows remote attackers to inject a

Routine

MEDIUM 5.4DOWNGRADE

CVE-2021-27677 is a medium-severity flaw (CVSS 5.4) affecting batflat. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Cross-site scripting (XSS) vulnerability in Galleries in Batflat CMS 1.3.6 allows remote attackers to inject arbitrary web script or HTML via the field name.

Why this priority

Public exploit reference

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

Risk facts

CVSS score	5.4 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.6% (top 50%)
CISA exploited list	No
Weakness	CWE-79
Published	2021-03-11
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: batflat

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

Am I affected?

Timeline

2021-03-11 17:15 UTCPublished CVE record published
2026-06-17 03:45 UTCUpdated Record last modified

batflat batflat DOWNGRADE

Affected: 1.3.6

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.3.6

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 1.3.6 (Debian / Ubuntu)

apt-cache madison batflat sudo apt install batflat=<VERSION_BEFORE_1.3.6> sudo apt-mark hold batflat

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

dnf --showduplicates list batflat sudo dnf downgrade batflat-<VERSION_BEFORE_1.3.6> sudo dnf versionlock add batflat

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-2021-27677?

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

Is CVE-2021-27677 being exploited?

CVE-2021-27677 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-2021-27677 affect?

CVE-2021-27677 affects batflat. Severity is medium (CVSS 5.4). Cross-site scripting (XSS) vulnerability in Galleries in Batflat CMS 1.3.6 allows remote attackers to inject arbitrary web script or HTML via the field name.

How urgent is CVE-2021-27677?

Priority 36/100. Public exploit reference

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References

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