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CVE

CVE-2026-27633

TinyWeb has Unbounded Content-Length Memory Exhaustion (DoS)
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CVE

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., clientmaxbody_size in nginx).

Package Versions Affected

Package Version
patch Availability
No items found.

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CVSS Version

Severity
Base Score
CVSS Version
Score Vector
C
H
U
8.7
-
4.0
CVSS: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/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
C
H
U
0
-
C
H
U
-

Related Resources

No items found.

References

https://www.masiutin.net/tinyweb-cve-2026-27633.html, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27633.json, https://github.com/maximmasiutin/TinyWeb/security/advisories/GHSA-992w-gmcm-fmgr, https://nvd.nist.gov/vuln/detail/CVE-2026-27633, https://github.com/maximmasiutin/TinyWeb/commit/1cb5a1d

Severity

0

CVSS Score
0
10

Basic Information

Ecosystem
Base CVSS
0
EPSS Probability
0.00142%
EPSS Percentile
0.33888%
Introduced Version
0
Fix Available
c78ef4a3c708bf3969e5b320c08f86ce8cd8feb3

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