Live › vulnerability › CVE-2026-33057
Go to dashboardMesop, a Python UI framework, has a flaw where an unauthenticated attacker sends a specially crafted Base64-encoded request body and executes arbitrary code on the server. Cloudflare's WAF now blocks this pattern, but the framework itself must be upgraded to remove the flaw.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-24 19:12 UTC, 0h before NVD. All times on this page are UTC.
Teams running Mesop below on a server reachable from the internet or an untrusted network are exposed, since the request body is the attack path. Applications that do not use Mesop, or that run it only on an internal machine with no untrusted access, are less exposed; the sources do not say whether specific deployment modes are safe.
1.2.3| Product | Ecosystem | Affected | Fixed in |
|---|---|---|---|
| mesop-dev mesop | vendor | < 1.2.3 | 1.2.3 |
pip show mesop or inspect the lockfile to find the installed Mesop version; anything below 1.2.3 is affected.1.2.3 or later.Each row is the first time that source carried this signal. The analyst’s rows are its own findings.
WAF Release - 2026-04-15 · Changelog
New updates and improvements at Cloudflare.
April 15, 2026
This week's release introduces a new detection for a critical Remote Code Execution (RCE) vulnerability in Mesop (CVE-2026-33057), alongside protections for high-impact vulnerabilities in Cisco Secure Firewall Management Center (CVE-2026-20079) and FortiClient EMS (CVE-2026-21643). Additionally, this release includes an update to our existing React Server DoS coverage to address recently identified resource exhaustion vectors (CVE-2026-23869).
Key Findings
Impact
Successful exploitation of these vulnerabilities could allow unauthenticated attackers to execute arbitrary code, gain administrative control over network management infrastructure, or trigger server-side resource exhaustion. Administrators are strongly encouraged to apply official vendor updates.
| Ruleset | Rule ID | Legacy Rule ID | Description | Previous Action | New Action | Comments |
|---|---|---|---|---|---|---|
| Cloudflare Managed Ruleset | ...aef9415b | N/A | Cisco Secure FMC - RCE via upgradeReadinessCall - CVE:CVE-2026-20079 | Log | Block | This is a new detection. |
| Cloudflare Managed Ruleset | ...ee7be621 | N/A | FortiClient EMS - Pre-Auth SQL Injection - CVE:CVE-2026-21643 | Log | Block | This is a new detection. |
| Cloudflare Managed Ruleset | ...c953a72b | N/A | Mesop - Remote Code Execution - Base64 Payload - CVE:CVE-2026-33057 | Log | Block | This is a new detection. |
| Cloudflare Managed Ruleset | ...50c08f6f | N/A | React Server - DOS - CVE:CVE-2026-23864 - 1 - Beta | Log | Block | This rule has been merged into the original rule "React Server - DOS - CVE:CVE-2026-23864 - 1" (ID: ...61680354) |
| Cloudflare Managed Ruleset | ...ebd81645 | N/A | XSS, HTML Injection - Link Tag - URI (beta) |
This page as .md · .json · in your agent: get_signal("CVE-2026-33057")
NVD data is provided by NIST and is public domain. Posts quoted belong to their authors.
| N/A |
| Disabled |
| This is a new detection. |
| Cloudflare Managed Ruleset | ...0af34bba | N/A | XSS, HTML Injection - Embed Tag - URI (beta) | N/A | Disabled | This is a new detection. |