vBulletin: Improper Protection of Alternate Path
CVE-2025-48827 is a critical-severity improper protection of alternate path vulnerability in vBulletin, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected vBulletin versions: 5.0.0 through 5.7.5; 6.0.0 through 6.0.3. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 75.6% chance of exploitation within 30 days, which is in the top 0.47% of all scored CVEs.
Exploitation in the next 30 days is more likely than not, according to EPSS.
What to do
- Check which version of vBulletin you run against the affected versions below, and install the vendor's latest release.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| vBulletin | vBulletin | 5.0.0 through 5.7.5; 6.0.0 through 6.0.3 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 10.0 | Critical | CNA (mitre.org) |
| CVSS 3.1 | 9.8 | Critical | NVD |
Official description
vBulletin 5.0.0 through 5.7.5 and 6.0.0 through 6.0.3 allows unauthenticated users to invoke protected API controllers' methods when running on PHP 8.1 or later, as demonstrated by the /api.php?method=protectedMethod pattern, as exploited in the wild in May 2025.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Protection of Alternate Path
The product does not sufficiently protect all possible paths that a user can take to access restricted functionality or resources.
How developers prevent this class of flaw
- Deploy different layers of protection to implement security in depth.
More Improper Protection of Alternate Path vulnerabilities (CWE-424)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- kevintel.com/CVE-2025-48827Third Party Advisory
Technical write-ups (may include proof of concept)
- karmainsecurity.com/dont-call-that-protected-method-vbulletin-rceExploit, Third Party Advisory
Other vulnerabilities in vBulletin
- 9.8 Critical severity
- 8.1 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
Recent Improper Protection of Alternate Path vulnerabilities
- 9.8 Critical severity
- 8.5 High severity
- 7.0 High severity
- 7.8 High severity
- 8.8 High severity
- 7.8 High severity
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