CVE-2026-27633: TinyWeb has Unbounded Content-Length Memory Exhaustion (DoS)
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., clientmaxbodysize in nginx).
Affected Software
Remediation
Patch Available
Event History
Frequently Asked Questions
What is the severity of CVE-2026-27633?
CVE-2026-27633 is a high severity Denial of Service (DoS) vulnerability due to unbounded memory exhaustion.
How do I fix CVE-2026-27633?
To fix CVE-2026-27633, upgrade TinyWeb to version 2.02 or later.
What type of attack does CVE-2026-27633 allow?
CVE-2026-27633 allows unauthenticated remote attackers to launch a Denial of Service (DoS) attack by sending malicious HTTP POST requests.
Which versions of TinyWeb are affected by CVE-2026-27633?
TinyWeb versions prior to 2.02 are affected by CVE-2026-27633.
Can CVE-2026-27633 be exploited over the internet?
Yes, CVE-2026-27633 can be exploited by remote attackers over the internet without authentication.