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🛡️ CVE-2025-48940 — mybb

🟠 CVSS 7.2 — High ✅ No Known Exploit CWE-22 NVD
7.2
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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 forum has not yet been installed; or the attacker is authenticated as a forum administrator). MyBB 1.8.39 resolves this issue.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs administrative privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability high.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: High — administrative rights are needed first.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: High — total loss, or loss the attacker controls.
  • Integrity impact: High — total loss, or loss the attacker controls.
  • Availability impact: High — total loss, or loss the attacker controls.

Weakness class

CVE-2025-48940 is classified as CWE-22: Path Traversal. A file path built from user input is not confined to the intended directory, letting an attacker reach files elsewhere on the filesystem.

Affected software

CVE-2025-48940 is recorded against 1 package.

  • mybb (fixed in 1.8.39)

Timeline and source

Published on 2 June 2025 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

github.com
github.com
mybb.com

Other advisories for this package

mybb has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-22: Path Traversal) in other software:

Details

Severity HIGH
CVSS Score 7.2
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
CWE CWE-22
Public Exploit ✅ No
Source NVD
Published 2025-06-02
Updated 2026-08-20
Modified 2026-06-17

Affected Packages

Software From version Fixed in
mybb — 1.8.39

Site Security Check

Is mybb part of your stack?

CVE-2025-48940 is rated CVSS 7.2 High. BotEraser scans your installation against known CVE records and tells you whether this vulnerability applies to the versions you actually run.

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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