vBulletin: Improper Protection of Alternate Path
CVE-2025-48828 is a high-severity improper protection of alternate path vulnerability in vBulletin, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected vBulletin versions: 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 57.3% chance of exploitation within 30 days, which is in the top 0.91% 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
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
- HighSuccess depends on conditions outside the attacker's control.
- 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:H/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 9.0 | Critical | CNA (mitre.org) |
| CVSS 3.1 | 8.1 | High | NVD |
Official description
Certain vBulletin versions might allow attackers to execute arbitrary PHP code by abusing Template Conditionals in the template engine. By crafting template code in an alternative PHP function invocation syntax, such as the "var_dump"("test") syntax, attackers can bypass security checks and execute arbitrary PHP code, 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: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- kevintel.com/CVE-2025-48828Third 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
- 9.8 Critical 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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