CVE-2026-22665
Fka Prompts.Chat ≤ 2026-03-24
Raw vector
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/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:XCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2026-22665 is a high-severity Improper Handling of Case Sensitivity (CWE-178) vulnerability in Fka Prompts.Chat. Its CVSS base score is 8.6 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Masquerading (T1036); ranked at the 26th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to AC-24 (Access Control Decisions) and AC-3 (Access Enforcement) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-22665, published on 2026-04-03, is an identity confusion vulnerability (CWE-178) in the prompts.chat application prior to commit 1464475. The issue arises from inconsistent case-sensitive and case-insensitive handling of usernames across write and read paths, enabling attackers to register case-variant usernames that bypass uniqueness checks during creation. This leads to non-deterministic username resolution, with a CVSS v3.1 base score of 8.1 (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N).
An attacker with low privileges (PR:L), such as a registered user, can exploit this vulnerability remotely over the network with low complexity and no user interaction required. By creating a case-variant username that matches a victim's canonical username, the attacker can impersonate the victim account, replace profile content displayed on canonical URLs, and inject attacker-controlled metadata and content across the platform, compromising confidentiality and integrity.
Mitigation is provided via commit 1464475df2698fb7ccd0cdbc382b0750466f891d, merged through pull request #1098 on the prompts.chat GitHub repository. Security practitioners should update affected prompts.chat instances to this commit or later to enforce consistent case handling and prevent bypasses. Further technical details are outlined in the VulnCheck advisory.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-18829
Vulnerability Data
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…
more
to impersonate victim accounts, replace profile content on canonical URLs, and inject attacker-controlled metadata and content across the platform.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Applying access control decisions to each request depends on accurate property determination that accounts for case differences.
Correct enforcement of authorizations for resource access structurally requires consistent case-sensitive handling of identifiers to avoid incorrect decisions.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices can catch and prevent case-sensitivity flaws during code review or testing, but fixing one CWE achieves negligible coverage of the broad control.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Secure SDLC practices should include case-sensitivity requirements in design and coding standards.
Application security requirements must specify case handling for identifiers and paths.
Architecture principles should enforce canonical, case-aware resource naming.
Secure coding guidelines must mandate explicit case handling to prevent inconsistent lookups.
Access-control rules that ignore case can allow unintended resource access.
Authentication logic must treat identifiers consistently to avoid bypass via case differences.