What’s Vulnerable › Vulnerabilities

CVE-2026-93421: Mesop: Unauthenticated ANSI Escape Sequence Injection in CSP Reporting Endpoint

• Severity: medium (CVSS 5.3 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-23 · updated 2026-09-30
• Weakness: CWE-117

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.

Affected products

• mesop-dev mesop: before 1.3.4

References

• https://github.com/mesop-dev/mesop/commit/f38c42a1d3eba246941ef8d7f645072d53c58785
• https://github.com/mesop-dev/mesop/pull/1397
• https://github.com/mesop-dev/mesop/releases/tag/v1.3.4
• https://github.com/mesop-dev/mesop/security/advisories/GHSA-g7f6-rxc4-qhph

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