CVE-2023-33386: MarsCTF 1.2.1 has an arbitrary file upload vulnerability in the interface for uploading attachments in the bac

This week

CRITICAL 9.8REMOTEDOWNGRADE

CVE-2023-33386 is a critical-severity flaw (CVSS 9.8) affecting marsctf. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

MarsCTF 1.2.1 has an arbitrary file upload vulnerability in the interface for uploading attachments in the background.

Why this priority

Critical severity
Public exploit reference
Remotely exploitable, no login, no user action

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

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.0% (top 37%)
CISA exploited list	No
Weakness	CWE-434
Published	2023-06-05
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: marsctf project

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

Am I affected?

Timeline

2023-06-05 15:15 UTCPublished CVE record published
2026-06-17 06:01 UTCUpdated Record last modified

marsctf project marsctf DOWNGRADE

Affected: 1.2.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.2.1

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 1.2.1 (Debian / Ubuntu)

apt-cache madison marsctf sudo apt install marsctf=<VERSION_BEFORE_1.2.1> sudo apt-mark hold marsctf

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

dnf --showduplicates list marsctf sudo dnf downgrade marsctf-<VERSION_BEFORE_1.2.1> sudo dnf versionlock add marsctf

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-2023-33386?

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

Is CVE-2023-33386 being exploited?

CVE-2023-33386 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-2023-33386 affect?

CVE-2023-33386 affects marsctf. Severity is critical (CVSS 9.8). MarsCTF 1.2.1 has an arbitrary file upload vulnerability in the interface for uploading attachments in the background.

How urgent is CVE-2023-33386?

Priority 60/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

References

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