Vulnerability report

Active exploitation observed Confirmed confidence Not in CISA KEV

CVE-2026-48611

phpBB

phpBB · 3.3.0 to <= 3.3.16

Watch CVE-2026-48611 Browse KEV feed
Severity
CVSS 9.8 · Critical
Confidence
Confirmed
Exploit status
Observed in sensors
EPSS
2.9%
First observed
19 Jul 2026
Last observed
11 Oct 2026

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2026-48611 is an unauthenticated vulnerability affecting phpBB. Improper authentication checks in the OAuth implementation allow account hijacking even when OAuth is not configured or enabled leading to...

Is it exploited?

Yes. Previdian sensors observed exploitation attempts with confirmed confidence.

Who is affected?

phpBB 3.3.0 to <= 3.3.16.

What should we do?

Patch immediately, validate internet-facing exposure, and monitor for matching requests.

Overview

phpBB

Improper authentication checks in the OAuth implementation allow account hijacking even when OAuth is not configured or enabled leading to unauthorized access in default installations.

phpBB Affected
phpBB
Through 3.3.16
Published
12 Jun 2026
Exploitation Reported
19 Jul 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

php nuclei_scanner

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

Previdian

Recorded 19 Jul 2026

Previdian independently recorded this as exploited after first seeing it in honeypot sensors.

Active exploitation observed

Previdian sensor

First observed 19 Jul 2026

Previdian first observed exploitation attempts targeting this vulnerability in our honeypot sensors.

Proof of concept available

GitHub

Recorded 13 Jun 2026

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

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Source Added
Previdian Sensors First 2026-07-20 07:57 UTC

Operational indicators for this CVE are listed under Detection.

Sensor telemetry

First-party evidence of exploitation activity

Previdian sensors recorded exploitation attempts targeting this vulnerability. The cards and chart show volume, unique attackers, and daily activity.

15

Attempts observed

13

Unique attacker IPs

10

Attacker countries

BG · CH · FR · HK · ID · JP · NL · SC · US · YE

11

Sensors observed

CVE-2026-48611 exploitation attempts over the last 88 days

Daily events observed by Previdian sensors

Updated 13 Oct 2026

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18 Jul 5 Aug 23 Aug 10 Sep 13 Oct

First observed 19 Jul 2026 · Last observed 11 Oct 2026

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Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
1
8
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

Attacker IP Indicators

Attacker IP indicators observed · available in Pro and Enterprise.

Sensor-derived attacker IP indicators are available to Pro and Enterprise accounts under Detection and through the Pro API.

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Scanner Artifacts

Scanner and exploit-framework references linked to this CVE.

Scanner Reference Detected
Nuclei https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-48611.yaml 06 Jul 2026

Risk and context

Severity, weaknesses, and research context

CVSS v3.0

9.8 Critical

Potential damage if exploited. Separate from whether attackers are using it.

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

2.9%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Improper Authentication CWE-287

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

Ethicalgrey/phpBB-CVE-2026-48611

github · Created 2026-08-30 15:35:30 UTC · 0 stars · AI assessment 90%

Automated PoC for CVE-2026-48611 — phpBB OAuth login_link authentication bypass

phpBB < 3.3.17 - Authentication Bypass

nuclei · Created Unknown

Timeline

From disclosure to observed exploitation

  1. 02:12 UTC

    Indicators of compromise added (13)

    Indicators of compromise recorded

  2. 02:12 UTC

    Observed by Previdian sensors

    Evidence-backed exploitation signal

  3. 04:31 UTC

    Public PoC available

    Public proof-of-concept code published

  4. 04:31 UTC

    Nuclei template available

    Scanner coverage available

  5. 02:27 UTC

    CVE published

    Vulnerability disclosed publicly

  6. 15:00 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2026-48611

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2026-48611",
  "confidence": "Confirmed",
  "cvss_score": 9.8,
  "cvss_estimated": false,
  "epss_score": 0.02888,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": true
  },
  "sensor_telemetry": { "attempts": 15, "sensors": 11 }
}