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Webrick CVE-2025-6442

| EUVDEUVD-2025-19113 MEDIUM
HTTP Request/Response Smuggling (CWE-444)
2025-06-25 zdi-disclosures@trendmicro.com GHSA-r995-q44h-hr64
Information Disclosure Debian Ubuntu Red Hat Webrick Suse Ruby Lang
5.9
CVSS 3.1 · NVD
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Vulnerability Assessment

Weakness
CWE
CWE-444
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V4 - API and Web Service HTTP request consistency
Impact

CVSS score of 5.9 (MEDIUM).
This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 15, 2026

Ruby WEBrick read_header HTTP Request Smuggling Vulnerability. This vulnerability allows remote attackers to smuggle arbitrary HTTP requests on affected installations of Ruby WEBrick. This issue is exploitable when the product is deployed behind an HTTP proxy that fulfills specific conditions.

The specific flaw exists within the read_headers method. The issue results from the inconsistent parsing of terminators of HTTP headers. An attacker can leverage this vulnerability to smuggle arbitrary HTTP requests. Was ZDI-CAN-21876.

Earlier versions of this analysis (1)
v1 Mar 15, 2026 - 23:19 CVSS 5.9

RemediationAI

A vendor patch is available. Apply it as soon as possible and verify the fix.

Affected VersionsENISA

WEBrick 1.8.1

Affected Packages

rubygems webrick fix: 1.8.2

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in rubygems

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

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Technical ContextAI · show details

This vulnerability is classified as HTTP Request/Response Smuggling (CWE-444).

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Severity by source

NVD PRIMARY 5.9 MEDIUM
AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
Ubuntu MEDIUM
SUSE 6.5 MEDIUM
AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N
Red Hat 6.5 MEDIUM

Primary rating from NVD.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

Lifecycle Timeline

2
Patch released
Mar 15, 2026 - 23:19 nvd
Patch available
CVE Published
Jun 25, 2025 - 17:15 nvd
MEDIUM 5.9

Executive ViewAI

Why It Matters

CVE-2025-6442 presents moderate security risk rated CVSS 5.9. Exploitation could compromise the security of affected deployments. A patch is available and should be applied during regular vulnerability management.

Business Impact: Low
Compensating Controls

Apply vendor patch. If patching is delayed: restrict network access and enable monitoring.

Threat Intelligence Overview

EPSS Score
0.1%
Top 78% exploitable
Data Quality
6 sources
Confidence: High
EUVD NVD CVE.org EPSS Vendor GitHub

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.1%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Defer
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
No
Human Impact
Low

Priority Score

30
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +30
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

More in Webrick

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CVE-2020-25613 HIGH
7.5 Oct 06

An issue was discovered in Ruby through 2.5.8, 2.6.x through 2.6.6, and 2.7.x through 2.7.1. Rated high severity (CVSS 7
CVE-2019-11879 MEDIUM
5.5 May 10

The WEBrick gem 1.4.2 for Ruby allows directory traversal if the attacker once had local access to create a symlink to a

Same weakness CWE-444 – HTTP Request/Response Smuggling

View all
CVE-2023-41265 CRITICAL POC
9.9
CVE-2026-88773 CRITICAL POC
9.3
CVE-2026-48710 MEDIUM POC
6.5
CVE-2021-33037 MEDIUM
5.3
CVE-2021-23336 MEDIUM POC
5.9
CVE-2025-55315 CRITICAL POC
9.9
CVE-2018-3907 CRITICAL POC
10.0
CVE-2024-10264 CRITICAL POC
9.8

Same technique Information Disclosure

View all
CVE-2019-2725 CRITICAL POC
9.8
CVE-2021-34523 CRITICAL POC
9.0
CVE-2013-2251 CRITICAL POC
9.8
CVE-2017-5638 CRITICAL POC
9.8
CVE-2025-24813 CRITICAL POC
9.8
CVE-2025-68613 HIGH POC
8.8
CVE-2015-1701 HIGH POC
7.8
CVE-2017-0147 HIGH POC
7.5

Vendor StatusVendor

Ubuntu

Priority: Medium
ruby-webrick
Release Status Version
oracular ignored end of life, was needs-triage
upstream released 1.9.1-1
jammy released 1.7.0-3ubuntu0.2
noble released 1.8.1-1ubuntu0.2
plucky released 1.8.1-1ubuntu1.1
questing released 1.9.1-1
jruby
Release Status Version
trusty needed -
xenial needed -
bionic needed -
focal needed -
jammy DNE -
noble not-affected vulnerable code not present
plucky not-affected vulnerable code not present
questing not-affected vulnerable code not present
upstream needs-triage -
ruby2.3
Release Status Version
jammy DNE -
noble DNE -
plucky DNE -
questing DNE -
upstream needs-triage -
xenial released 2.3.1-2~ubuntu16.04.16+esm11
ruby2.5
Release Status Version
jammy DNE -
noble DNE -
plucky DNE -
questing DNE -
upstream needs-triage -
bionic released 2.5.1-1ubuntu1.16+esm6
ruby2.7
Release Status Version
jammy DNE -
noble DNE -
plucky DNE -
questing DNE -
upstream needs-triage -
focal released 2.7.0-5ubuntu1.18+esm3
USN-7709-1 USN-7840-1

Debian

ruby-webrick
Release Status Fixed Version Urgency
bookworm vulnerable 1.8.1-1 -
trixie fixed 1.9.1-1 -
forky, sid fixed 1.9.2-1 -
(unstable) fixed 1.9.1-1 -

SUSE

Severity: Medium
Product Status
Image SLES15-SP3-Micro-5-2-BYOS-Azure Image SLES15-SP3-Micro-5-2-BYOS-EC2-HVM Image SLES15-SP3-Micro-5-2-BYOS-GCE Image SLES15-SP4-BYOS Image SLES15-SP4-BYOS-Azure Image SLES15-SP4-BYOS-EC2 Image SLES15-SP4-BYOS-GCE Image SLES15-SP4-HPC-BYOS Image SLES15-SP4-HPC-BYOS-Azure Image SLES15-SP4-HPC-BYOS-EC2 Image SLES15-SP4-HPC-BYOS-GCE Image SLES15-SP4-HPC-EC2 Image SLES15-SP4-HPC-GCE Image SLES15-SP4-Hardened-BYOS Image SLES15-SP4-Hardened-BYOS-Azure Image SLES15-SP4-Hardened-BYOS-EC2 Image SLES15-SP4-Hardened-BYOS-GCE Image SLES15-SP4-Manager-Proxy-4-3-BYOS Image SLES15-SP4-Manager-Proxy-4-3-BYOS-Azure Image SLES15-SP4-Manager-Proxy-4-3-BYOS-EC2 Image SLES15-SP4-Manager-Proxy-4-3-BYOS-GCE Image SLES15-SP4-Manager-Server-4-3-BYOS Image SLES15-SP4-Manager-Server-4-3-BYOS-Azure Image SLES15-SP4-Manager-Server-4-3-BYOS-EC2 Image SLES15-SP4-Manager-Server-4-3-BYOS-GCE Image SLES15-SP4-SAP Image SLES15-SP4-SAP-Azure Image SLES15-SP4-SAP-Azure-LI-BYOS Image SLES15-SP4-SAP-Azure-LI-BYOS-Production Image SLES15-SP4-SAP-Azure-VLI-BYOS Image SLES15-SP4-SAP-Azure-VLI-BYOS-Production Image SLES15-SP4-SAP-BYOS Image SLES15-SP4-SAP-BYOS-Azure Image SLES15-SP4-SAP-BYOS-EC2 Image SLES15-SP4-SAP-BYOS-GCE Image SLES15-SP4-SAP-EC2 Image SLES15-SP4-SAP-GCE Image SLES15-SP4-SAP-Hardened Image SLES15-SP4-SAP-Hardened-Azure Image SLES15-SP4-SAP-Hardened-BYOS Image SLES15-SP4-SAP-Hardened-BYOS-Azure Image SLES15-SP4-SAP-Hardened-BYOS-EC2 Image SLES15-SP4-SAP-Hardened-BYOS-GCE Image SLES15-SP4-SAP-Hardened-GCE Image SLES15-SP4-SAPCAL Image SLES15-SP4-SAPCAL-Azure Image SLES15-SP4-SAPCAL-EC2 Image SLES15-SP4-SAPCAL-GCE Image SLES15-SP5-Azure-3P Image SLES15-SP5-Azure-Basic Image SLES15-SP5-Azure-Standard Image SLES15-SP5-BYOS-Azure Image SLES15-SP5-BYOS-EC2 Image SLES15-SP5-BYOS-GCE Image SLES15-SP5-EC2 Image SLES15-SP5-GCE Image SLES15-SP5-HPC-Azure Image SLES15-SP5-HPC-BYOS-Azure Image SLES15-SP5-HPC-BYOS-EC2 Image SLES15-SP5-HPC-BYOS-GCE Image SLES15-SP5-Hardened-BYOS-Azure Image SLES15-SP5-Hardened-BYOS-EC2 Image SLES15-SP5-Hardened-BYOS-GCE Image SLES15-SP5-SAP-Azure-3P Image SLES15-SP5-SAP-Azure-LI-BYOS Image SLES15-SP5-SAP-Azure-LI-BYOS-Production Image SLES15-SP5-SAP-Azure-VLI-BYOS Image SLES15-SP5-SAP-Azure-VLI-BYOS-Production Image SLES15-SP5-SAP-BYOS-Azure Image SLES15-SP5-SAP-BYOS-EC2 Image SLES15-SP5-SAP-BYOS-GCE Image SLES15-SP5-SAP-Hardened-Azure Image SLES15-SP5-SAP-Hardened-BYOS-Azure Image SLES15-SP5-SAP-Hardened-BYOS-EC2 Image SLES15-SP5-SAP-Hardened-BYOS-GCE Image SLES15-SP5-SAP-Hardened-GCE Image SLES15-SP5-SAPCAL-Azure Image SLES15-SP5-SAPCAL-EC2 Image SLES15-SP5-SAPCAL-GCE Image SLES15-SP6 Image SLES15-SP6-Azure-3P Image SLES15-SP6-Azure-Basic Image SLES15-SP6-Azure-Standard Image SLES15-SP6-BYOS Image SLES15-SP6-BYOS-Azure Image SLES15-SP6-BYOS-EC2 Image SLES15-SP6-BYOS-GCE Image SLES15-SP6-EC2 Image SLES15-SP6-GCE Image SLES15-SP6-HPC Image SLES15-SP6-HPC-Azure Image SLES15-SP6-HPC-BYOS Image SLES15-SP6-HPC-BYOS-Azure Image SLES15-SP6-HPC-BYOS-EC2 Image SLES15-SP6-HPC-BYOS-GCE Image SLES15-SP6-HPC-EC2 Image SLES15-SP6-HPC-GCE Image SLES15-SP6-Hardened-BYOS Image SLES15-SP6-Hardened-BYOS-Azure Image SLES15-SP6-Hardened-BYOS-EC2 Image SLES15-SP6-Hardened-BYOS-GCE Image SLES15-SP6-SAP Image SLES15-SP6-SAP-Azure Image SLES15-SP6-SAP-Azure-3P Image SLES15-SP6-SAP-Azure-LI-BYOS Image SLES15-SP6-SAP-Azure-LI-BYOS-Production Image SLES15-SP6-SAP-Azure-VLI-BYOS Image SLES15-SP6-SAP-Azure-VLI-BYOS-Production Image SLES15-SP6-SAP-BYOS Image SLES15-SP6-SAP-BYOS-Azure Image SLES15-SP6-SAP-BYOS-EC2 Image SLES15-SP6-SAP-BYOS-GCE Image SLES15-SP6-SAP-EC2 Image SLES15-SP6-SAP-GCE Image SLES15-SP6-SAP-Hardened Image SLES15-SP6-SAP-Hardened-Azure Image SLES15-SP6-SAP-Hardened-BYOS Image SLES15-SP6-SAP-Hardened-BYOS-Azure Image SLES15-SP6-SAP-Hardened-BYOS-EC2 Image SLES15-SP6-SAP-Hardened-BYOS-GCE Image SLES15-SP6-SAP-Hardened-EC2 Image SLES15-SP6-SAP-Hardened-GCE Image SLES15-SP6-SAPCAL Image SLES15-SP6-SAPCAL-Azure Image SLES15-SP6-SAPCAL-EC2 Image SLES15-SP6-SAPCAL-GCE Affected
Image SLES15-SP7-Azure-3P Image SLES15-SP7-Azure-Basic Image SLES15-SP7-Azure-Standard Image SLES15-SP7-BYOS-Azure Image SLES15-SP7-BYOS-EC2 Image SLES15-SP7-BYOS-GCE Image SLES15-SP7-EC2 Image SLES15-SP7-GCE Image SLES15-SP7-GCE-3P Image SLES15-SP7-HPC-Azure Image SLES15-SP7-HPC-BYOS-Azure Image SLES15-SP7-HPC-BYOS-EC2 Image SLES15-SP7-HPC-BYOS-GCE Image SLES15-SP7-Hardened-BYOS-Azure Image SLES15-SP7-Hardened-BYOS-EC2 Image SLES15-SP7-Hardened-BYOS-GCE Image SLES15-SP7-SAP-Azure Image SLES15-SP7-SAP-Azure-3P Image SLES15-SP7-SAP-Azure-LI-BYOS-Production Image SLES15-SP7-SAP-Azure-VLI-BYOS-Production Image SLES15-SP7-SAP-BYOS-Azure Image SLES15-SP7-SAP-BYOS-EC2 Image SLES15-SP7-SAP-BYOS-GCE Image SLES15-SP7-SAP-EC2 Image SLES15-SP7-SAP-GCE Image SLES15-SP7-SAP-GCE-3P Image SLES15-SP7-SAP-Hardened-Azure Image SLES15-SP7-SAP-Hardened-BYOS-Azure Image SLES15-SP7-SAP-Hardened-BYOS-EC2 Image SLES15-SP7-SAP-Hardened-BYOS-GCE Image SLES15-SP7-SAP-Hardened-GCE Image SLES15-SP7-SAPCAL-Azure Image SLES15-SP7-SAPCAL-EC2 Image SLES15-SP7-SAPCAL-GCE Affected
SUSE Enterprise Storage 7.1 Fixed
SUSE Linux Enterprise Desktop 15 SP6 SUSE Linux Enterprise High Performance Computing 15 SP6 SUSE Linux Enterprise Module for Basesystem 15 SP6 SUSE Linux Enterprise Server 15 SP6 SUSE Linux Enterprise Server for SAP Applications 15 SP6 Fixed
SUSE Linux Enterprise Desktop 15 SP7 SUSE Linux Enterprise High Performance Computing 15 SP7 SUSE Linux Enterprise Module for Basesystem 15 SP7 SUSE Linux Enterprise Server 15 SP7 SUSE Linux Enterprise Server for SAP Applications 15 SP7 Fixed

References

Advisories & patches
PATCH https://github.com/ruby/webrick/commit/ee60354bcb84ec33b9245e1d1aa6e1f7e8132101#diff-ad02984d873efb089aa51551bc6b7d307a53e0ba1ac439e91d69c2e58a478864 ADVISORY https://github.com/rubysec/ruby-advisory-db/blob/master/gems/webrick/CVE-2025-6442.yml ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2025-6442 ADVISORY https://ubuntu.com/security/notices/USN-7709-1 ADVISORY https://ubuntu.com/security/notices/USN-7840-1 ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:02739/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:4264/ REF https://www.zerodayinitiative.com/advisories/ZDI-25-414/

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