CVE-2025-57783Network attack vector

Unauthenticated access-control bypass via substring header matching

Published Jan 26, 2026 · Updated Jan 26, 2026

HTTP request smuggling in Hiawatha Webserver 8.5 through 11.7 allows remote attackers to access restricted server resources. The fetch_request function uses substring-based header lookup, causing text embedded within another header field to be treated as Content-Length or chunked transfer metadata. No authentication is required; conflicting message boundaries can bypass access controls, hijack sessions, or inject requests.

CVSS severity5.3
Medium
EPSS probability0.48%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTTP request smuggling in Hiawatha Webserver 8.5 through 11.7 allows remote attackers to access restricted server resources. The fetch_request function uses substring-based header lookup, causing text embedded within another header field to be treated as Content-Length or chunked transfer metadata. No authentication is required; conflicting message boundaries can bypass access controls, hijack sessions, or inject requests.

The record

CVE
CVE-2025-57783
Published
Jan 26, 2026
Updated
Jan 26, 2026
Vendor
Hiawatha
Product
Hiawatha Webserver
Classifications
CWE-444, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 26, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 26, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=11.7 <=8.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Hiawatha · Hiawatha Webserverversion=11.7 <=8.5

Published CVSS scores

5.3CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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