CVE-2026-29199
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedphpBB before 3.3.16 is vulnerable to Host Header Injection that can lead to password rest link poisoning. When force_server_vars is disabled, the servers hostname may be extracted from the HTTP Host header which is used to generate the password reset link URL. An attacker who can manipulate the Host header (e.g. through misconfigured host setup or missing header validation by the webserver) can cause password reset emails to contain a link pointing to an attacker-controlled domain, potentially leading to account takeover.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidencephpBB before 3.3.16 is vulnerable to Host Header Injection. When the force_server_vars setting is disabled, the application extracts the server hostname from the HTTP Host header and uses it to construct password reset URLs. An attacker who can manipulate the Host header can inject an attacker-controlled domain into password reset links sent via email, enabling account takeover.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 3.3.16CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
-
Determine installed phpBB versionAccess the phpBB admin control panel and navigate to the System tab to view the version, or check the version file in your phpBB installation directoryAffected if version is below 3.3.16
-
Check force_server_vars configuration settingIn the phpBB admin panel, go to Server Configuration > Server Settings and locate the 'force_server_vars' option. Alternatively, query the phpbb_config table in the database for force_server_vars valueAffected if force_server_vars is set to disabled or 0 (the vulnerable configuration)
-
Verify Host header usage in password resetExamine the password reset code or confirm that the application constructs reset URLs based on the HTTP Host header when force_server_vars is disabled. This is the default behavior in affected versionsAffected if Password reset URLs are generated using the HTTP Host header rather than a configured server variable
You are affected if your phpBB version is below 3.3.16 AND the force_server_vars setting is disabled, allowing the application to use the HTTP Host header for constructing password reset URLs.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped3.3.16
Enable force_server_vars in phpBB configuration or implement server-side validation of the Host header to ensure only trusted domains are used when generating password reset links.
phpBB 3.3.16
- 1. Back up your phpBB database and files before performing any upgrade
- 2. Download phpBB 3.3.16 or later from the official phpBB website (https://www.phpbb.com/downloads/)
- 3. Extract the upgrade package to a temporary location
- 4. Copy the new files over your existing installation, preserving the config.php file
- 5. Run the database update script by visiting your forum's URL (the system will prompt if updates are needed)
- 6. As an additional hardening measure, enable force_server_vars in config.php by adding: $force_server_vars = true;
- 7. Verify the fix by testing the password reset functionality
- 8. Clear any caches through the admin control panel
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation3.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-29199 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-29199 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data