CVE-2025-59843: Flag Forge is a Capture The Flag (CTF) platform

Routine

MEDIUM 5.3REMOTEUPGRADE

CVE-2025-59843 is a medium-severity flaw (CVSS 5.3) affecting flagforge. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Flag Forge is a Capture The Flag (CTF) platform. From versions 2.0.0 to before 2.3.2, the public endpoint /api/user/[username] returns user email addresses in its JSON response. The fix, intended for release in 2.3.1 but only available starting in version 2.3.2, removes email addresses from public API responses while keeping the endpoint publicly accessible. Users should upgrade to version 2.3.2 or later to eliminate exposure. There are no workar

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 64%)
CISA exploited list	No
Weakness	CWE-359
Published	2025-09-26
Last modified	2026-10-09

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

Last updated 2026-10-09 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2025-09-26 16:15 UTCPublished CVE record published
2026-10-09 10:10 UTCUpdated Record last modified

flagforge flagforge UPGRADE

Affected: >= 2.0 and < 2.3.1

Fixed in: 2.3.1

Safe to downgrade to: a release before 2.0

1. Check installed version

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

2. UPGRADE to 2.3.1 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade flagforge

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 2.0 (Debian / Ubuntu)

apt-cache madison flagforge sudo apt install flagforge=<VERSION_BEFORE_2.0> sudo apt-mark hold flagforge

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

dnf --showduplicates list flagforge sudo dnf downgrade flagforge-<VERSION_BEFORE_2.0> sudo dnf versionlock add flagforge

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-2025-59843?

flagforge: upgrade to 2.3.1. Exact commands for each OS are on this page.

Is CVE-2025-59843 being exploited?

CVE-2025-59843 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-2025-59843 affect?

CVE-2025-59843 affects flagforge. Severity is medium (CVSS 5.3). Flag Forge is a Capture The Flag (CTF) platform. From versions 2.0.0 to before 2.3.2, the public endpoint /api/user/[username] returns user email addresses in its JSON response. The fix, intended for release in 2.3.1 but only available star

How urgent is CVE-2025-59843?

Priority 32/100. Remotely exploitable, no login, no user action

Related CVEs

CVE-2025-59841 CRITICAL 9.8 UPGRADE Flag Forge is a Capture The Flag (CTF) platform
CVE-2025-59826 HIGH 7.6 DOWNGRADE Flag Forge is a Capture The Flag (CTF) platform
CVE-2025-61777 CRITICAL 9.4 UPGRADE Flag Forge is a Capture The Flag (CTF) platform
CVE-2025-59932 HIGH 8.6 UPGRADE Flag Forge is a Capture The Flag (CTF) platform
CVE-2026-21868 HIGH 7.5 UPGRADE Flag Forge is a Capture The Flag (CTF) platform

References

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