EUVD-2026-36380
GHSA-575v-33q9-fpgm
Severity by source
AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H
Attacker needs no phpBB credentials (PR:N) but must win an OAuth state race (AC:H) and trick a logged-in victim into clicking (UI:R); takeover yields full C/I but no direct availability loss.
Primary rating from Vendor (hackerone).
CVSS VectorVendor: hackerone
CVSS:3.0/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H
Lifecycle Timeline
1DescriptionCVE.org
Improper state verification in the OAuth implementation could allow an attacker to manipulate the authentication flow and cause a victim’s account to be linked to an attacker-controlled account. This can result in unauthorized account linking and potential account takeover.
AnalysisAI
Account takeover in phpBB via OAuth state-verification flaw enables remote attackers to link a victim's forum account to an attacker-controlled identity provider account. Successful exploitation requires the victim to click an attacker-crafted link while authenticated, after which the attacker can authenticate as the victim through the linked external provider. …
Unlock full vulnerability intelligence
- Risk assessment & exploitation conditions
- Attack chain visualization
- Remediation with exact patch versions
- Threat intelligence from 22 sources
- Personal watchlist & email alerts
Free forever · No credit card required
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires that the phpBB instance has an OAuth authentication provider enabled and configured (Google, Facebook, or similar social login), and that the victim is logged into the forum and clicks an attacker-supplied link while that session is active - both reflected in the CVSS metrics PR:L (victim must be authenticated) and UI:R (click required). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.0 score of 8.0 (AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H) reflects a high-impact, scope-changed CSRF requiring some preconditions: low privileges (a logged-in victim session), user interaction (clicking a link), and high attack complexity (winning the OAuth flow race or coercing the right click). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker initiates an OAuth authorization request at an identity provider using their own account, captures the resulting authorization code or pre-seeded state, and lures a logged-in phpBB user (typically an administrator) into clicking a crafted callback URL on the target forum. The phpBB OAuth handler accepts the response without correctly verifying that the state parameter belongs to the victim's session and links the attacker's external identity to the victim's forum account, after which the attacker logs in via the social provider and assumes the victim's identity. |
| Remediation | Patch availability is indicated by the vendor advisory at https://www.phpbb.com/community/viewtopic.php?t=2672170, but the exact fixed version is not present in the supplied data - administrators should consult that thread and upgrade to the patched release noted there (Patch available per vendor advisory). … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
24 hours: Confirm phpBB deployment across the organization and verify whether OAuth authentication is actively configured and in use. …
Sign in for detailed remediation steps and compensating controls.
Threat intelligence, references, and detailed analysis are available after sign-in.
Account hijacking in phpBB is possible due to improper authentication checks in the OAuth implementation, affecting defa
Host header injection in phpBB versions 3.0.0 through 3.3.15 enables password reset link poisoning when force_server_var
Privilege escalation in phpBB allows an authenticated administrator with limited rights to grant themselves permissions
SQL injection in phpBB forum software allows authenticated users to execute arbitrary SQL queries through a flawed profi
Same weakness CWE-352 – Cross-Site Request Forgery (CSRF)
View allShare
External POC / Exploit Code
Leaving vuln.today