What is CVE-2026-27633?

CVE-2026-27633 is a high-severity vulnerability in Maximmasiutin Tinyweb, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2026-02-26.

How severe is CVE-2026-27633?

High severity. CVSS v3 base score is 7.5 out of 10.

Resource exhaustion in Maximmasiutin Tinyweb

CVE-2026-27633

TinyWeb is a web server (HTTP, HTTPS) written in Delphi for Win32. Versions prior to version 2.02 have a Denial of Service (DoS) vulnerability via memory exhaustion. Unauthenticated remote attackers can send an HTTP POST request to the server with an exceptionally large `Content-Length` header (e.g., `2147483647`). The server continuously allocates memory for the request body (`EntityBody`) while streaming the payload without enforcing any maximum limit, leading to all available memory being consumed and causing the server to crash. Anyone hosting services using TinyWeb is impacted. Version 2.02 fixes the issue. The patch introduces a `CMaxEntityBodySize` limit (set to 10MB) for the maximum size of accepted payloads. As a temporary workaround if upgrading is not immediately possible, consider placing the server behind a Web Application Firewall (WAF) or reverse proxy (like nginx or Cloudflare) configured to explicitly limit the maximum allowed HTTP request body size (e.g., `client_max_body_size` in nginx).

Vulnerability class: DoS (Denial of Service)

Published 2026-02-26 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.009 (60.0th percentile), scored 2026-10-24.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 60th percentile — 60.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.008 · newest: 0.009 · change: +0.001

Affected products

Maximmasiutin Tinyweb — versions < 2.02
Ritlabs Tinyweb

Weakness classification (CWE)

References

github.com/maximmasiutin/TinyWeb/security/advisories/GHSA-992w-gmcm-fmgr (Vendor Advisory)
github.com/maximmasiutin/TinyWeb/commit/1cb5a1d (Patch)
www.masiutin.net/tinyweb-cve-2026-27633.html (Third Party Advisory)

Frequently asked questions

What is CVE-2026-27633?: CVE-2026-27633 is a high-severity vulnerability in Maximmasiutin Tinyweb, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2026-02-26.
How severe is CVE-2026-27633?: High severity. CVSS v3 base score is 7.5 out of 10.