CVE-2025-48940: MyBB is free and open source forum software

Q: How do I fix CVE-2025-48940?

mybb: upgrade to 1.8.39. Exact commands for each OS are on this page.

Q: Is CVE-2025-48940 being exploited?

CVE-2025-48940 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2025-48940 affect?

CVE-2025-48940 affects mybb. Severity is high (CVSS 7.2). MyBB is free and open source forum software. Prior to version 1.8.39, the upgrade component does not validate user input properly, which allows attackers to perform local file inclusion (LFI) via a specially crafted parameter value. In orde

Routine

HIGH 7.2UPGRADE

CVE-2025-48940 is a high-severity flaw (CVSS 7.2) affecting mybb. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

MyBB is free and open source forum software. Prior to version 1.8.39, the upgrade component does not validate user input properly, which allows attackers to perform local file inclusion (LFI) via a specially crafted parameter value. In order to exploit the vulnerability, the installer must be unlocked (no `install/lock` file present) and the upgrade script must be accessible (by re-installing the forum via access to `install/index.php`; when the

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	7.2 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	High
User interaction	None
EPSS exploit chance	0.5% (top 55%)
CISA exploited list	No
Weakness	CWE-22
Published	2025-06-02
Last modified	2026-06-17

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

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

Am I affected?

Timeline

2025-06-02 16:15 UTCPublished CVE record published
2026-06-17 09:30 UTCUpdated Record last modified

mybb mybb UPGRADE

Affected: < 1.8.39

Fixed in: 1.8.39

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 1.8.39 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade mybb

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

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-2025-48940?

mybb: upgrade to 1.8.39. Exact commands for each OS are on this page.

Is CVE-2025-48940 being exploited?

CVE-2025-48940 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-2025-48940 affect?

CVE-2025-48940 affects mybb. Severity is high (CVSS 7.2). MyBB is free and open source forum software. Prior to version 1.8.39, the upgrade component does not validate user input properly, which allows attackers to perform local file inclusion (LFI) via a specially crafted parameter value. In orde

How urgent is CVE-2025-48940?

Priority 37/100. High severity

Software pages

PHP vulnerabilities

Related CVEs

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CVE-2025-29460 HIGH 7.6 DOWNGRADE An issue in MyBB 1.8.38 allows a remote attacker to obtain sensitive information via the Add Mycode function
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CVE-2025-29458 HIGH 7.6 DOWNGRADE An issue in MyBB 1.8.38 allows a remote attacker to obtain sensitive information via the Change Avatar functio
CVE-2025-29457 HIGH 7.6 DOWNGRADE An issue in MyBB 1.8.38 allows a remote attacker to obtain sensitive information via the Import a Theme functi

References

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