CVE-2026-40571 Overview
CVE-2026-40571 is a missing authorization vulnerability [CWE-862] in NamelessMC, website software used by Minecraft server operators. The flaw affects version 2.2.4 and resides in core/classes/Misc/ProfilePostReactionContext.php. The component verifies that a wall post exists but does not enforce blocked or private profile visibility checks. Authenticated low-privileged users can add reactions to posts on private profiles or profiles that have blocked them. NamelessMC addressed the issue in version 2.2.5.
Critical Impact
Authenticated attackers can bypass profile privacy controls to interact with wall posts on private or blocking profiles, violating user privacy boundaries.
Affected Products
- NamelessMC version 2.2.4
- NamelessMC core/classes/Misc/ProfilePostReactionContext.php component
- Minecraft community sites running vulnerable NamelessMC deployments
Discovery Timeline
- 2026-06-02 - CVE-2026-40571 published to NVD
- 2026-06-03 - Last updated in NVD database
Technical Details for CVE-2026-40571
Vulnerability Analysis
The vulnerability is a missing authorization check in NamelessMC's profile post reaction handler. The class ProfilePostReactionContext.php performs only a single existence check against the target wall post. It does not consult the privacy state of the profile owning that post. As a result, the application accepts reaction submissions against posts that the requesting user should not be able to see or interact with.
The impact is limited to integrity and confidentiality of profile interaction state. An attacker cannot escalate privileges or execute code through this flaw. However, the issue undermines the trust model of the private profile and user blocking features.
Root Cause
The root cause is incomplete access control logic in ProfilePostReactionContext.php. The handler validates only the existence of the wall post identifier supplied by the client. It omits the secondary check that compares the requesting user against the profile owner's privacy settings and block list. This pattern is classified under [CWE-862] Missing Authorization.
Attack Vector
Exploitation requires an authenticated account with low privileges on the target NamelessMC site. The attacker submits a reaction request referencing the identifier of a wall post belonging to a private profile or a profile that has blocked the attacker. The server processes the reaction because it never evaluates the privacy or block relationship. No user interaction by the victim is required.
The vulnerability mechanism is described in the GitHub Security Advisory GHSA-47hr-jj6c-rqf9. No public proof-of-concept exploit code has been published.
Detection Methods for CVE-2026-40571
Indicators of Compromise
- Reaction records on profile posts where the reacting user is on the profile owner's block list.
- Reaction activity on posts belonging to profiles configured as private from accounts that are not approved followers.
- Unexpected notification entries delivered to profile owners who restrict their wall visibility.
Detection Strategies
- Audit the NamelessMC database for profile_post_reactions entries that correlate with user_blocks rows between the reacting user and the post owner.
- Compare reaction timestamps against the date of the upgrade to version 2.2.5 to identify pre-patch abuse.
- Review web server access logs for POST requests to the profile post reaction endpoint originating from accounts that lack visibility to the targeted profile.
Monitoring Recommendations
- Enable verbose application logging on profile interaction endpoints to capture user identifiers and target post identifiers.
- Forward NamelessMC application and web server logs to a central SIEM for correlation against blocked-user and private-profile metadata.
- Alert on bursts of reaction submissions from a single account against multiple distinct profile owners.
How to Mitigate CVE-2026-40571
Immediate Actions Required
- Upgrade NamelessMC to version 2.2.5 or later, which contains the authorization fix in ProfilePostReactionContext.php.
- Review user accounts for abusive behavior and suspend accounts that have repeatedly targeted private or blocking profiles.
- Notify users whose privacy expectations may have been violated while version 2.2.4 was in production.
Patch Information
NamelessMC released version 2.2.5 as the fixed release. The patch enforces blocked and private-profile visibility checks inside the reaction handler before persisting the reaction. Refer to the GitHub Security Advisory GHSA-47hr-jj6c-rqf9 for the upstream fix details.
Workarounds
- If immediate upgrade is not possible, restrict access to the profile post reaction route at the web server or reverse proxy layer for untrusted user groups.
- Temporarily disable the profile wall reactions feature in the NamelessMC administration panel until the patched version is deployed.
- Increase moderator review of profile interaction activity until upgrade completion.
# Upgrade NamelessMC to the patched release
cd /var/www/nameless
git fetch --tags
git checkout v2.2.5
php upgrade.php
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
