CVE-2021-27280: OS Command injection vulnerability in mblog 3.5.0 allows attackers to execute arbitrary code via crafted theme

This month

HIGH 7.8DOWNGRADE

CVE-2021-27280 is a high-severity flaw (CVSS 7.8) affecting mblog. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

OS Command injection vulnerability in mblog 3.5.0 allows attackers to execute arbitrary code via crafted theme when it gets selected.

Why this priority

High severity
Public exploit reference

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

Risk facts

CVSS score	7.8 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	1.0% (top 38%)
CISA exploited list	No
Weakness	CWE-434
Published	2023-05-08
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: mblog project

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

Am I affected?

Timeline

2023-05-08 14:15 UTCPublished CVE record published
2026-06-17 03:44 UTCUpdated Record last modified

mblog project mblog DOWNGRADE

Affected: 3.5.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.5.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 3.5.0 (Debian / Ubuntu)

apt-cache madison mblog sudo apt install mblog=<VERSION_BEFORE_3.5.0> sudo apt-mark hold mblog

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

dnf --showduplicates list mblog sudo dnf downgrade mblog-<VERSION_BEFORE_3.5.0> sudo dnf versionlock add mblog

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-2021-27280?

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

Is CVE-2021-27280 being exploited?

CVE-2021-27280 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-2021-27280 affect?

CVE-2021-27280 affects mblog. Severity is high (CVSS 7.8). OS Command injection vulnerability in mblog 3.5.0 allows attackers to execute arbitrary code via crafted theme when it gets selected.

How urgent is CVE-2021-27280?

Priority 48/100. High severity; Public exploit reference

Related CVEs

CVE-2025-9647 MEDIUM 4.3 UPGRADE A weakness has been identified in mtons mblog up to 3.5.0
CVE-2024-28713 CRITICAL 9.8 DOWNGRADE An issue in Mblog Blog system v.3.5.0 allows an attacker to execute arbitrary code via a crafted file to the t
CVE-2025-9433 MEDIUM 4.3 UPGRADE A vulnerability was found in mtons mblog up to 3.5.0
CVE-2025-9432 MEDIUM 4.3 UPGRADE A vulnerability has been found in mtons mblog up to 3.5.0
CVE-2025-9431 MEDIUM 4.3 UPGRADE A flaw has been found in mtons mblog up to 3.5.0

References

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