CVE-2026-29199: Phpbb/phpbb PhpBB Has Password Reset Link Vulnerability

HIGH
Advisory Identifier: GHSA-7gm6-w7mx-58cr
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CVSS 8.1
CWE-640
Published
Advisory Summary

CVE-2026-29199 is a HIGH (CVSS 8.1) phpbb has password reset link vulnerability (CWE-640: Weak Password Recovery Mechanism for Forgotten Password) affecting Phpbb/phpbb libraries in the Packagist ecosystem. The issue involves phpbb has password reset link poisoning via host header injection. Remediation is available by upgrading affected packages to version 3.3.16, 4.0.0-a2.

CVE-2026-29199 at a Glance

CVE Identifier CVE-2026-29199
GHSA Identifier GHSA-7gm6-w7mx-58cr
Severity HIGH
CVSS v3.1 Base Score 8.1
CWE Classification CWE-640: Weak Password Recovery Mechanism for Forgotten Password
Affected Product Phpbb/phpbb
Package Ecosystem Packagist
Published Date
Last Updated

Security Impact

CVSS: 8.1

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability None (A:N)

How to Fix CVE-2026-29199

To remediate this vulnerability, upgrade all affected Phpbb/phpbb dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

phpbb/phpbb fixed: 3.3.16 
Upgrade phpbb/phpbb to 3.3.16
phpbb/phpbb fixed: 4.0.0-a2 
Upgrade phpbb/phpbb to 4.0.0-a2
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for phpbb/phpbb

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-29199, inspect your project dependencies for Phpbb/phpbb:

inspect dependencies for phpbb/phpbb

Analyze the terminal output to locate any version of Phpbb/phpbb in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.3.16), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-640: Weak Password Recovery Mechanism for Forgotten Password, where the product contains a mechanism for users to recover or change their passwords without knowing the original password, but the mechanism is weak. In Phpbb/phpbb, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

phpBB 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.

CVE-2026-29199 Affected Phpbb/phpbb Versions

2 component(s)
Fixed Versions:
3.3.164.0.0-a2
Product / Package Ecosystem Affected Versions Fixed Version
phpbb/phpbb
 Packagist
≥ 3.0.0
< 3.3.16
3.3.16
phpbb/phpbb
 Packagist
≥ 4.0.0-a1
< 4.0.0-a2
All 1 versions
4.0.0-a1
4.0.0-a2

References

NVD — CVE-2026-29199 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-29199
hackerone.com/reports/3543246 WEB
https://hackerone.com/reports/3543246
blog.phpbb.com/2026/04/27/phpbb-4-... WEB
https://blog.phpbb.com/2026/04/27/phpbb-4-0-0-a2-release
Phpbb/phpbb Source Repository REPOSITORY
https://github.com/phpbb/phpbb-app
www.phpbb.com/community/viewtopic... WEB
https://www.phpbb.com/community/viewtopic.php?t=2671024

Frequently Asked Questions

What is CVE-2026-29199?
CVE-2026-29199 is a security vulnerability in Phpbb/phpbb involving phpBB has Password Reset Link Poisoning via Host Header injection under CWE-640: Weak Password Recovery Mechanism for Forgotten Password.
Which Phpbb/phpbb versions are affected?
Affected versions include releases prior to 3.3.16, 4.0.0-a2 across affected packages: phpbb/phpbb.
What version fixes CVE-2026-29199?
Upgrading to 3.3.16, 4.0.0-a2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is phpbb/phpbb affected?
Yes, phpbb/phpbb is affected in releases prior to 3.3.16, 4.0.0-a2. Upgrade your dependency to 3.3.16, 4.0.0-a2 or later.
What is the CVSS score of CVE-2026-29199?
CVE-2026-29199 has a CVSS v3.1 base score of 8.1 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N.
What CWE is associated with CVE-2026-29199?
CVE-2026-29199 is classified under CWE-640: Weak Password Recovery Mechanism for Forgotten Password (The product contains a mechanism for users to recover or change their passwords without knowing the original password, but the mechanism is weak.).
How can I check Packagist dependencies for CVE-2026-29199?
Run the dependency tree command: 'inspect dependencies for phpbb/phpbb'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-7gm6-w7mx-58cr",
  "modified" : "2026-06-18T20:07:10Z",
  "published" : "2026-05-04T09:31:09Z",
  "aliases" : [ "CVE-2026-29199" ],
  "summary" : "phpBB has Password Reset Link Poisoning via Host Header injection",
  "details" : "phpBB 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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "phpbb/phpbb"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "3.0.0"
      }, {
        "fixed" : "3.3.16"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "phpbb/phpbb"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.0.0-a1"
      }, {
        "fixed" : "4.0.0-a2"
      } ]
    } ],
    "versions" : [ "4.0.0-a1" ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-29199"
  }, {
    "type" : "WEB",
    "url" : "https://hackerone.com/reports/3543246"
  }, {
    "type" : "WEB",
    "url" : "https://blog.phpbb.com/2026/04/27/phpbb-4-0-0-a2-release"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/phpbb/phpbb-app"
  }, {
    "type" : "WEB",
    "url" : "https://www.phpbb.com/community/viewtopic.php?t=2671024"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-640" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-18T20:07:10Z",
    "nvd_published_at" : "2026-05-04T07:15:59Z"
  }
}