Mesop: Unauthenticated ANSI Escape Sequence Injection in CSP Reporting Endpoint (CVE-2026-93421) | HOL Guard CVE

Medium · CVSS 5.3CVE-2026-93421GHSA-G7F6-RXC4-QHPH

Mesop: Unauthenticated ANSI Escape Sequence Injection in CSP Reporting Endpoint

Answer in brief

CVE-2026-93421 records a Medium severity (CVSS 5.3) vulnerability in Mesop: Unauthenticated ANSI Escape Sequence Injection in CSP Reporting Endpoint. The current sources do not mark it as known exploited. The current feed maps mesop-dev/mesop (generic), mesop (pip). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 23, 2026Updated Sep 23, 2026Source checked Sep 23, 2026First seen by HOL Sep 23, 2026Material review Sep 23, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 5.3
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

CVSS is 5.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps mesop-dev/mesop (generic), mesop (pip). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
mesop-dev/mesopgeneric	<1.3.4	1.3.4
mesoppip	<=1.3.3	1.3.4

Recommended response

Check inventory. Check lockfiles and deployed manifests for mesop-dev/mesop, mesop.
Review the reported fix. Update mesop-dev/mesop to 1.3.4; mesop to 1.3.4 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 23, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 23, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 23, 2026

Sources and claim methodology

Upstream source description

Mesop is a Python-based UI framework that allows users to build web applications. Prior to 1.3.4, the unauthenticated /__csp__ endpoint passes attacker-controlled document-uri, blocked-uri, and violated-directive values to the csp_report handler in mesop/server/static_file_serving.py, which prints them to standard output without neutralizing terminal control sequences. When an operator views the resulting logs in an ANSI-capable terminal, injected ANSI or VT100 sequences can clear or reposition the display, hide text, or present forged messages, reducing the integrity of monitoring and incident-response output. This issue is fixed in version 1.3.4.

Quoted source text, attributed separately from HOL analysis.