What is CVE-2025-57783?

CVE-2025-57783 is a medium-severity vulnerability in Hiawatha Web Server, classified under CWE-444 INCONSISTENT INTERPRETATION OF HTTP REQUESTS ('HTTP REQUEST SMUGGLING'). CVSS score: 5.3/10. Published 2026-01-26.

How severe is CVE-2025-57783?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Vulnerability in Hiawatha Web Server

CVE-2025-57783

Improper header parsing may lead to request smuggling has been identified in Hiawatha webserver version 11.7 which allows an unauthenticated attacker to access restricted resources managed by Hiawatha webserver.

Published 2026-01-26 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.005 (39.0th percentile), scored 2026-10-01.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 39th percentile — 39.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: +0.000

Affected products

Hiawatha Web Server — versions 11.7
Hiawatha-Webserver Hiawatha — versions 11.7

References

gitlab.com/hsleisink/hiawatha/-/blame/master/src/http.c (Product)

Frequently asked questions

What is CVE-2025-57783?: CVE-2025-57783 is a medium-severity vulnerability in Hiawatha Web Server, classified under CWE-444 INCONSISTENT INTERPRETATION OF HTTP REQUESTS ('HTTP REQUEST SMUGGLING'). CVSS score: 5.3/10. Published 2026-01-26.
How severe is CVE-2025-57783?: Medium severity. CVSS v3 base score is 5.3 out of 10.