CVE-2025-59841: Flag Forge is a Capture The Flag (CTF) platform

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CRITICAL 9.8REMOTEUPGRADE

CVE-2025-59841 is a critical-severity flaw (CVSS 9.8) 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. In versions from 2.2.0 to before 2.3.1, the FlagForge web application improperly handles session invalidation. Authenticated users can continue to access protected endpoints, such as /api/profile, even after logging out. CSRF tokens are also still valid post-logout, which can allow unauthorized actions. This issue has been patched in version 2.3.1.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 67%)
CISA exploited list	No
Weakness	CWE-384, CWE-613
Published	2025-09-25
Last modified	2026-10-11

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

Last updated 2026-10-11 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2025-09-25 16:15 UTCPublished CVE record published
2026-10-11 20:10 UTCUpdated Record last modified

flagforge flagforge UPGRADE

Affected: >= 2.2 and < 2.3.1

Fixed in: 2.3.1

Safe to downgrade to: a release before 2.2

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 2.2 (Debian / Ubuntu)

apt-cache madison flagforge sudo apt install flagforge=<VERSION_BEFORE_2.2> 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_2.2> 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-2025-59841?

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

Is CVE-2025-59841 being exploited?

CVE-2025-59841 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-2025-59841 affect?

CVE-2025-59841 affects flagforge. Severity is critical (CVSS 9.8). Flag Forge is a Capture The Flag (CTF) platform. In versions from 2.2.0 to before 2.3.1, the FlagForge web application improperly handles session invalidation. Authenticated users can continue to access protected endpoints, such as /api/pro

How urgent is CVE-2025-59841?

Priority 48/100. Critical severity; Remotely exploitable, no login, no user action

Related CVEs

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-2025-59843 MEDIUM 5.3 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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