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pH7Builder EUVDEUVD-2026-97066

| CVE-2026-108903 MEDIUM
Reliance on Untrusted Inputs in a Security Decision (CWE-807)
2026-10-11 disclosure@vulncheck.com GHSA-q5mq-9wc6-h8x8
6.9
CVSS 4.0 · Vendor: vulncheck
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Request CAPTCHA-free form (login/search)
  2. Delivery
    Capture its valid form ID
  3. Exploit
    Replay ID with signup/contact/comment payload
  4. Execution
    Pass Form::isValid() without CAPTCHA
  5. Impact
    Automate mass abuse and spam

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V2 - Validation and Business Logic Trusted input validation
Exploitation Conditions

No special conditions beyond running a pH7Builder (pH7 Social Dating CMS) instance before version 19.3.0 - the flaw is reachable remotely and unauthenticated (PR:N) against default configurations because PFBC Form::isValid() trusts a client-chosen form ID (the $_POST submit field) rather than the actual target form. Exploitation specifically requires the attacker to first load any CAPTCHA-free form (e.g., login or search) to obtain a valid form ID, then submit that ID with contact, comment, forum, invite, or signup data. Limiting factors: impact is confined to bypassing CAPTCHA/anti-automation on these public forms (VI:L) - there is no resulting data disclosure, authentication bypass, or code execution, so realistic harm is spam and automated-abuse rather than system compromise.

Impact

This is a moderate-severity anti-automation control bypass, not a high-impact breach. The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N) confirms remote, low-complexity, unauthenticated reachability, but the impact is deliberately scoped low: VI:L with VC:N and VA:N means the only consequence is unauthorized integrity effects (automated form submissions / abuse), with no confidentiality loss and no availability impact - consistent with CWE-807 (reliance on an untrusted client-supplied form ID in a security decision). No EPSS score, KEV listing, or public POC was provided, so there is no signal of active or widespread exploitation; the only code artifact is the vendor FIX commit (4758d7d), which is a patch, not an exploit. Net: this is a real but low-urgency issue - easy to trigger and useful for spammers/scrapers against pH7Builder sites, but it does not grant account takeover, data access, or code execution. The 'Authentication Bypass' tag somewhat overstates it; the flaw bypasses CAPTCHA/form validation, not authentication itself, so decision-makers should treat it as an abuse/spam-prevention gap rather than an access-control breach.

Exploit ScenarioDerived

An attacker programmatically requests a CAPTCHA-free pH7Builder form (such as login or search) to obtain a valid form ID, then replays that ID alongside signup, contact, comment, forum, or invite payloads so that PFBC Form::isValid() accepts the submission without a CAPTCHA check. This lets them script mass fake-account registration, comment/contact spam, and invite abuse against a default installation. No public exploit code was provided, but the technique is straightforward to automate given the low attack complexity.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 11, 2026

CAPTCHA and anti-automation checks protecting public forms in pH7Builder (pH7 Social Dating CMS) before 19.3.0 can be bypassed by unauthenticated remote attackers who supply a client-chosen form ID to the PFBC Form::isValid() routine. An attacker loads any CAPTCHA-free form such as login or search to obtain a valid form identifier, then submits that identifier together with contact, comment, forum, invite, or signup data, causing the application to accept the input without the intended human-verification step. Per the independent assessment this is a moderate-severity anti-automation control bypass (CVSS 3.1 AV:N/AC:L/PR:N/UI:N with only low integrity impact) - there is no authentication bypass, data disclosure, or code execution, so realistic harm is spam, fake-account creation, and automated abuse; no public exploit code and no confirmed active exploitation were identified at time of analysis, and the issue is fixed in 19.3.0.

RemediationAI

Upgrade to pH7Builder 19.3.0 or later - vendor-released patch: 19.3.0 - which pins the PFBC Form::isValid() argument to a server-side hard-coded form ID; the corresponding upstream fix is commit 4758d7d2ebfd5772faa25ef728c14f8f452e82f4 (see https://github.com/pH7Software/pH7-Social-Dating-CMS/commit/4758d7d2ebfd5772faa25ef728c14f8f452e82f4) and the advisory at https://www.vulncheck.com/advisories/ph7builder-before-19.3.0-captcha-bypass-via-client-chosen-form-id. If an immediate upgrade is not possible, apply compensating controls that target the abuse surface rather than the validation logic: add server-side enforcement at the controller level so each endpoint only accepts its own form ID (validating the POST submit field against a whitelist per route) - this is the nearest functional equivalent of the patch but requires code changes across every affected core and admin123 form; enable rate limiting, throttling, or a WAF rule on the signup, contact, comment, forum, and invite endpoints to blunt automated submissions, accepting that legitimate high-volume users may be throttled; and require email verification plus moderation queues for signups, invitations, and comments so machine-generated content is held before publication, at the cost of added latency in user onboarding. Note that IP- or session-based CAPTCHA re-challenges alone do not address the root cause, because the bypass stems from trusting the client-chosen form identifier.

Affected VersionsENISA

ph7builder 0 <19.3.0

Affected Packages

euvd ph7builder fix: 19.3.0

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

pH7Builder is a PHP-based social dating CMS that uses PFBC (PHP Form Builder Class) for form rendering and validation. The root cause is CWE-807, Reliance on Untrusted Inputs in a Security Decision: controllers called \PFBC\Form::isValid($_POST['submit_<form>']) where the argument was taken directly from the client-supplied POST body instead of being pinned to the form actually being handled. Because PFBC resolves the CAPTCHA/validation token against whichever form ID the caller passes, an attacker can name a form that carries no CAPTCHA (for example the login or search form) while delivering payload data intended for a CAPTCHA-protected form such as contact, comment, forum, invite, or signup. The upstream fix replaces the attacker-controlled value with a hard-coded string literal (for example Form::isValid('form_change_password'), Form::isValid('form_config'), Form::isValid('form_add_admin')), so validation is always tied to the server-side form definition. The affected code paths span core forms (ChangePassword, ConfigFile, CountryRestriction, DeleteUser, ResendActivation) and admin123 module forms (AddAdmin, AddFakeProfiles, AddUser, Ads, AnalyticsApi, BlockCountry, DisableModule and others), confirming the pattern was systemic rather than isolated. The flaw is network-reachable and requires no privileges (PR:N, UI:N in the provided vector), and the assessed impact is limited to integrity loss (VI:L) on anti-automation controls.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (vulncheck) PRIMARY 6.9 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
vuln.today AI 5.3 MEDIUM

Remote, low-complexity, unauthenticated reach (AV:N/AC:L/PR:N/UI:N); only a low integrity effect from bypassing CAPTCHA to submit abusive form data, with no confidentiality or availability impact.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (vulncheck).

CVSS VectorVendor: vulncheck

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
None
Vulnerable system: Confidentiality
None
Vulnerable system: Integrity
Low
Vulnerable system: Availability
None
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

Lifecycle Timeline

1
Patch available
Oct 11, 2026 - 16:02 EUVD

DescriptionCVE.org

pH7Builder (pH7 Social Dating CMS) before 19.3.0 contains a CAPTCHA bypass vulnerability that allows unauthenticated attackers to skip form validation by supplying a client-chosen form ID to PFBC Form::isValid(). Attackers can load a CAPTCHA-free form like login or search, then submit its ID with contact, comment, forum, invite or signup data to automate abuse.

Threat Intelligence Overview

EPSS Score
0.3%
Top 82% exploitable
Prevalence
Low
niche open-source social dating CMS, limited production footprint
Social Media
2
Sightings
Data Quality
5 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.3%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact· derived
Medium

Priority Score

34
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +34
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

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