CVE-2025-46171: vBulletin 3.8.7 is vulnerable to a denial-of-service condition via the misc.php?do=buddylist endpoint

Routine

MEDIUM 5.4DOWNGRADE

CVE-2025-46171 is a medium-severity flaw (CVSS 5.4) affecting vbulletin. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

vBulletin 3.8.7 is vulnerable to a denial-of-service condition via the misc.php?do=buddylist endpoint. If an authenticated user has a sufficiently large buddy list, processing the list can consume excessive memory, exhausting system resources and crashing the forum.

Why this priority

Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.4 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.3% (top 77%)
CISA exploited list	No
Weakness	CWE-400
Published	2025-07-23
Last modified	2026-07-05

Publisher (CNA): MITRE · Vendor: vbulletin

Last updated 2026-07-05 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2025-07-23 16:15 UTCPublished CVE record published
2026-07-05 01:21 UTCUpdated Record last modified

vbulletin vbulletin DOWNGRADE

Affected: 3.8.7

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.8.7

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 3.8.7 (Debian / Ubuntu)

apt-cache madison vbulletin sudo apt install vbulletin=<VERSION_BEFORE_3.8.7> sudo apt-mark hold vbulletin

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list vbulletin sudo dnf downgrade vbulletin-<VERSION_BEFORE_3.8.7> sudo dnf versionlock add vbulletin

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-2025-46171?

vbulletin: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2025-46171 being exploited?

CVE-2025-46171 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-2025-46171 affect?

CVE-2025-46171 affects vbulletin. Severity is medium (CVSS 5.4). vBulletin 3.8.7 is vulnerable to a denial-of-service condition via the misc.php?do=buddylist endpoint. If an authenticated user has a sufficiently large buddy list, processing the list can consume excessive memory, exhausting system resourc

How urgent is CVE-2025-46171?

Priority 30/100. Public exploit reference

Software pages

PHP vulnerabilities

Related CVEs

CVE-2025-48828 CRITICAL 9.0 DOWNGRADE Certain vBulletin versions might allow attackers to execute arbitrary PHP code by abusing Template Conditional
CVE-2025-48827 CRITICAL 10.0 UPGRADE vBulletin 5.0.0 through 5.7.5 and 6.0.0 through 6.0.3 allows unauthenticated users to invoke protected API con

References

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