Passenger
CVE-2025-26803
MEDIUM
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A06:2021 - Vulnerable and Outdated Components
ASVS 5.0
V15 - Secure Coding and Architecture Variable initialization
|
| Impact | CVSS score of 5.3 (MEDIUM). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required. EPSS exploitation probability: 0.60%. |
| Exploit ScenarioDerived | A remote attacker could access uninitialized memory causing crashes or information disclosure by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability. |
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Alert meAnalysisAIv1 – Mar 28, 2026
The http parser in Phusion Passenger 6.0.21 through 6.0.25 before 6.0.26 allows a denial of service during parsing of a request with an invalid HTTP method. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Use of Uninitialized Resource vulnerability could allow attackers to access uninitialized memory causing crashes or information disclosure.
RemediationAI
A vendor patch is available. Apply the latest security update as soon as possible. Initialize all variables, use compiler warnings for uninitialized access, use memory-safe languages.
Affected Packages
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.
Technical ContextAI · show details
This vulnerability is classified as Use of Uninitialized Resource (CWE-908), which allows attackers to access uninitialized memory causing crashes or information disclosure. The http parser in Phusion Passenger 6.0.21 through 6.0.25 before 6.0.26 allows a denial of service during parsing of a request with an invalid HTTP method. Affected products include: Phusion Passenger. Version information: through 6.0.25.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Primary rating from NVD.
CVSS VectorNVD
Lifecycle Timeline
2DescriptionCVE.org
The http parser in Phusion Passenger 6.0.21 through 6.0.25 before 6.0.26 allows a denial of service during parsing of a request with an invalid HTTP method.
Executive ViewAI
Organizations using Phusion Passenger 6.0.21 should be aware of moderate risk from CVE-2025-26803 rated CVSS 5.3. Exploitation could compromise the security of affected deployments. A patch is available and should be applied during regular vulnerability management.
Apply vendor patch. If patching is delayed: restrict network access and enable monitoring.
Threat Intelligence Overview
NVD
CVE.org
EPSS
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.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.
Affected Products (CPE)CVE.org
During the spawning of a malicious Passenger-managed application, SpawningKit in Phusion Passenger 5.3.x before 5.3.2 al
An Insecure Permissions vulnerability in SpawningKit in Phusion Passenger 5.3.x before 5.3.2 causes information disclosu
In Phusion Passenger before 5.1.0, a known /tmp filename was used during passenger-install-nginx-module execution, which
An Incorrect Access Control vulnerability in SpawningKit in Phusion Passenger 5.3.x before 5.3.2 allows a Passenger-mana
A race condition in the nginx module in Phusion Passenger 3.x through 5.x before 5.3.2 allows local escalation of privil
An issue was discovered in switchGroup() in agent/ExecHelper/ExecHelperMain.cpp in Phusion Passenger before 5.3.2. Rated
In agent/Core/SpawningKit/Spawner.h in Phusion Passenger 5.1.10 (fixed in Passenger Open Source 5.1.11 and Passenger Ent
Phusion Passenger gem before 3.0.21 and 4.0.x before 4.0.5 for Ruby allows local users to cause a denial of service (pre
ext/common/ServerInstanceDir.h in Phusion Passenger gem before 4.0.6 for Ruby allows local users to gain privileges or p
Phusion Passenger 4.0.37 allows local users to write to certain files and directories via a symlink attack on (1) contro
Phusion Passenger before 4.0.37 allows local users to write to certain files and directories via a symlink attack on (1)
Exploit-DB