CVE-2026-61511

Published Jul 27, 2026

Last updated 5 days ago

Overview

AI description

Automated description summarized from trusted sources.

CVE-2026-61511 is an eval injection vulnerability affecting vBulletin versions 5.x through 5.7.5 and 6.x through 6.2.1. The flaw resides within the `vB5_Template_Runtime::runMaths()` method in the template runtime, where an insufficiently restrictive regular expression filter allows crafted input to bypass intended character restrictions before being processed by PHP's `eval()` function. Unauthenticated remote attackers can exploit this vulnerability to execute arbitrary PHP code. This is achieved by supplying specially crafted input through the `pagenav[pagenumber]` parameter via the unauthenticated `ajax/render` template route. No authentication, session, or user interaction is required for successful exploitation, and attackers can utilize phpfuck-style encoding to construct their payloads.

Description
vBulletin 5.x through 5.7.5 and 6.x through 6.2.1 contains an eval injection vulnerability in the vB5_Template_Runtime::runMaths() method within the template runtime that allows unauthenticated remote attackers to execute arbitrary PHP code by supplying crafted input through the pagenav[pagenumber] parameter. Attackers can exploit the insufficiently restrictive regex filter by using phpfuck-style encoding with permitted characters to inject and execute arbitrary PHP code via the unauthenticated ajax/render template route without any authentication.
Source
disclosure@vulncheck.com
NVD status
Deferred

Risk scores

CVSS 4.0

Type
Secondary
Base score
9.3
Impact score
-
Exploitability score
-
Vector string
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Severity
CRITICAL

CVSS 3.1

Type
Secondary
Base score
9.8
Impact score
5.9
Exploitability score
3.9
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Severity
CRITICAL

Weaknesses

disclosure@vulncheck.com
CWE-95

Social media

Hype score is a measure of social media activity compared against trending CVEs from the past 12 months. Max score 100.

Hype score

5

  1. ๐Ÿšจ CVE-2026-61511: A critical unauthenticated RCE vulnerability affects vBulletin 5.x/6.x via runMaths eval injection. #vBulletin #RCE #CVE #CyberSecurity

    @ThreatWire_

    2 Aug 2026

    2268 Impressions

    2 Retweets

    15 Likes

    4 Bookmarks

    0 Replies

    0 Quotes

  2. CVE-2026-61511: critical unauthenticated RCE in vBulletin 5.x/6.x via runMaths eval injection. Get the Nuclei detection template and scan with Sn1per. https://t.co/sCsYL3Uv5L #CVE-2026-61511 #bugbounty #redteam #offsec #netsec #infosec #poc https://t.co/JxdGQfBs0G

    @xer0dayz

    1 Aug 2026

    1077 Impressions

    7 Retweets

    21 Likes

    7 Bookmarks

    0 Replies

    0 Quotes

  3. CVE-2026-61511: critical unauthenticated RCE in vBulletin 5.x/6.x via runMaths eval injection. Get the Nuclei detection template and scan with Sn1per. https://t.co/48xuw7wyMA #CVE-2026-61511 #bugbounty #redteam #offsec #netsec #infosec #poc https://t.co/g8tw8MVx2A

    @Sn1perSecurity

    1 Aug 2026

    135 Impressions

    0 Retweets

    0 Likes

    0 Bookmarks

    0 Replies

    0 Quotes

  4. ๐Ÿšจ๐Ÿšจ๐Ÿšจ๐Ÿšจ # CVE-2026-61511 #vBulletin RCE Exploit Kit CVE-2026-61511 is an unauthenticated Remote Code Execution vulnerability in vBulletin forums affecting versions 5.0.0-5.7.5 and 6.0.0-6.2.1. Look who's back ๐Ÿ˜Ž BrokenSecยฎ #0days #exploit #RCE #CVE #security #hacki

    @YogSoth0

    29 Jul 2026

    805 Impressions

    5 Retweets

    21 Likes

    7 Bookmarks

    3 Replies

    0 Quotes

  5. ๐Ÿšจ CVE-2026-61511: vBulletin < 6.2.2 Eval Injection RCE via vb5/template/runtime.php Critical Vulnerability Alert! vBulletin is affected by CVE-2026-61511. Full Vulnerability Details & Analysis at DarkEye: ๐Ÿ”— https://t.co/PheaYhNSYY ๐Ÿ” Identify Targets via ZoomEye

    @zoomeye_team

    28 Jul 2026

    1267 Impressions

    4 Retweets

    14 Likes

    2 Bookmarks

    0 Replies

    0 Quotes

  6. Public exploit details for CVE-2026-61511 show an unauthenticated RCE in vBulletin's template engine, reaching PHP eval() via vB5_Template_Runtime::runMaths(). Affects unpatched forums. #vBulletin #CVE-2026-61511 #PHP https://t.co/Cmte8v93jZ

    @TweetThreatNews

    27 Jul 2026

    188 Impressions

    0 Retweets

    0 Likes

    0 Bookmarks

    0 Replies

    0 Quotes

  7. ๐Ÿšจ CVE-2026-61511 โ€” CVSS 9.8/10 โ–ˆโ–ˆโ–ˆโ–ˆโ–ˆโ–ˆโ–ˆโ–ˆโ–ˆโ–ˆ vBulletin 5.x through 5.7.5 and 6.x through 6.2.1 contains an eval injection vulnerability in the... Severity: CRITICAL Patch now. #cybersecurity #CVE https://t.co/gvOFCwbyGb

    @OrizonCyber

    27 Jul 2026

    36 Impressions

    0 Retweets

    0 Likes

    0 Bookmarks

    1 Reply

    0 Quotes