VulnerabilityAnalyzed

CVE-2026-27633

Versions prior to version 2.02 have a Denial of Service (DoS) vulnerability via memory exhaustion.

HIGH 8.7EPSS 0.44%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.44%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

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).

CVSS 4.0: 8.7 HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
EPSS: 0.44% probability · 37th percentile
CISA KEV: Not listed
Weakness: CWE-400, CWE-770
Affected: ritlabs/tinyweb
Source: security-advisories@github.com

References

https://github.com/maximmasiutin/TinyWeb/commit/1cb5a1dPatch
https://github.com/maximmasiutin/TinyWeb/security/advisories/GHSA-992w-gmcm-fmgrVendor Advisory
https://www.masiutin.net/tinyweb-cve-2026-27633.htmlThird Party Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.