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Prompts Chat CVE-2026-22665

| EUVDEUVD-2026-18829 HIGH
Improper Handling of Case Sensitivity (CWE-178)
2026-04-03 VulnCheck GHSA-pcq9-m482-5r7j
8.6
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
    Login with valid account
  2. Exploit
    Create case-variant username bypassing uniqueness checks
  3. Execution
    Resolve to victim's canonical account
  4. Impact
    Inject malicious profile content and metadata

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Case sensitivity handling
Exploitation Conditions

Attacker requires an authenticated account on prompts.chat prior to commit 1464475. No victim interaction needed. Attacker creates case-variant usernames exploiting inconsistent case-sensitive/case-insensitive handling to bypass uniqueness checks and impersonate victim accounts or inject malicious content.

Impact

Real-world risk is moderate-to-high for platforms hosting user-generated content. The CVSS 8.6 score reflects genuine technical severity: network exploitation with low complexity and no user interaction makes this readily exploitable by any authenticated user (PR:L). However, impact is constrained to the vulnerable platform (SC:N/SI:N/SA:N indicate no subsequent system compromise). No EPSS score or KEV listing suggests limited current exploitation visibility, but the attack's simplicity (create case-variant account, monitor non-deterministic resolution) means manual exploitation requires minimal sophistication. Vendor patch availability (commit 1464475) eliminates technical barriers to remediation. Primary risk vectors include reputation damage from profile impersonation, SEO poisoning via canonical URL hijacking, and trust exploitation in community platforms where username identity anchors content authenticity. SSVC assessment: exploitation status is public (VulnCheck advisory), automatable with moderate effort (requires authenticated session establishment), technical impact is partial (user account takeover but not platform-wide compromise). Organizations running self-hosted prompts.chat instances should prioritize patching; users on hosted services depend on operator upgrade cycles.

Exploit ScenarioDerived

An authenticated attacker registers username 'Alice' on prompts.chat after victim 'alice' already exists, exploiting case-insensitive validation bypass. The platform's non-deterministic user resolution randomly serves either profile when users navigate to /alice, allowing the attacker to poison the canonical URL with malicious prompt templates containing phishing links or misinformation. When search engines index the page during attacker-controlled resolution windows, the fraudulent content becomes associated with the victim's established reputation. Simultaneously, the attacker monitors resolution patterns to harvest victim profile views, extracting confidential prompt metadata. Attack requires only low-privilege authenticated access with no user interaction (CVSS PR:L/UI:N), making mass exploitation feasible through automated account creation scripts.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Apr 03, 2026

Identity confusion in prompts.chat (prior to commit 1464475) enables authenticated attackers to impersonate users and hijack profile URLs by creating case-variant usernames (e.g., 'Alice' vs 'alice'). Inconsistent case-handling between write and read operations allows bypass of uniqueness validation, letting attackers inject malicious content on canonical victim profiles. EPSS data not available; no public exploit identified at time of analysis, though attack complexity is low (CVSS:4.0 AC:L) requiring only low-privilege access (PR:L). VulnCheck disclosed this vulnerability with vendor patch released via GitHub commit.

RemediationAI

Vendor-released patch: commit 1464475df2698fb7ccd0cdbc382b0750466f891d available at github.com/f/prompts.chat/commit/1464475df2698fb7ccd0cdbc382b0750466f891d. Administrators running self-hosted instances should immediately update to this commit or any subsequent release incorporating the fix by pulling latest changes from the upstream repository and redeploying. The patch implements consistent case-insensitive username handling across all database operations, eliminating case-variant registration and enforcing deterministic user resolution. For organizations unable to patch immediately, temporary risk reduction measures include implementing application-layer username normalization (force lowercase on registration and authentication), auditing existing user databases for case-variant duplicates and merging or removing conflicting accounts, and monitoring authentication logs for suspicious case-variant login attempts. Review pull request github.com/f/prompts.chat/pull/1098 for implementation details and verify database schema changes are applied during upgrade. No configuration workaround fully mitigates the vulnerability without code-level fixes.

Affected VersionsENISA

prompts.chat 0 <1464475df2698fb7ccd0cdbc382b0750466f891d

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Technical ContextAI · show details

This vulnerability (CWE-178: Improper Handling of Case Sensitivity) affects prompts.chat, a web platform for sharing AI prompts. The root cause stems from architectural inconsistency where username validation at account creation enforces case-insensitive uniqueness checks, but subsequent data retrieval operations use case-sensitive lookups. This creates a race condition in identity resolution: when multiple case variants of a username exist (e.g., 'user', 'User', 'USER'), non-deterministic resolution logic may return different user records depending on query context. The CPE identifier (cpe:2.3:a:f:prompts.chat:*:*:*:*:*:*:*:*) indicates this affects the prompts.chat application from vendor 'f' (GitHub user/organization). The CVSS 4.0 vector shows network-accessible exploitation (AV:N) with low complexity (AC:L) and no attack timing constraints (AT:N), requiring low privileges (PR:L) and no user interaction (UI:N), resulting in high confidentiality and integrity impact to the vulnerable system (VC:H/VI:H) with no subsequent system impact propagation.

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Severity by source

Vendor (VulnCheck) PRIMARY 8.6 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (VulnCheck) · only source for this CVE.

CVSS VectorVendor: VulnCheck

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

Lifecycle Timeline

2
Patch released
Apr 03, 2026 - 20:45 nvd
Patch available
CVE Published
Apr 03, 2026 - 20:28 nvd
HIGH 8.6

DescriptionCVE.org

prompts.chat prior to commit 1464475 contains an identity confusion vulnerability due to inconsistent case-sensitive and case-insensitive handling of usernames across write and read paths, allowing attackers to create case-variant usernames that bypass uniqueness checks. Attackers can exploit non-deterministic username resolution to impersonate victim accounts, replace profile content on canonical URLs, and inject attacker-controlled metadata and content across the platform.

Executive ViewAI

Why It Matters

A case-sensitivity flaw in prompts.chat allows authenticated users to hijack existing user accounts by registering nearly-identical usernames that bypass validation controls, directly compromising confidentiality and integrity of user data across multi-tenant instances. Organizations operating prompts.chat must immediately patch to prevent account takeover and unauthorized access to sensitive conversation data and user profiles.

Business Impact: High
Compensating Controls

Apply vendor patch. Interim mitigations pending patching: (1) Restrict account creation permissions to administrators only; (2) Implement supplementary validation requiring usernames differ by more than case alone before account activation; (3) Monitor and alert on profile metadata changes or canonical URL access anomalies; (4) Disable prompts.chat instance if account takeover risk is unacceptable until patch deployed.

Threat Intelligence Overview

EPSS Score
0.0%
Top 92% exploitable
Social Media
1
Sightings
Data Quality
7 sources
Confidence: High
EUVD NVD CVE.org EPSS Vulnrichment CIRCL GitHub VulDB

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 HIGH
CISA KEV No
Public POC No
EPSS 0.0%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
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
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact
High
Technical Impact
Total

Priority Score

43
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +43
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

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