VulnerabilityPublished 25 Jun 2026

CVE-2026-56122: rickknowles Winstone Servlet Container · Path Traversal

Affects rickknowles Winstone Servlet ContainerSource CVE Database V5

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Not known to be exploited · CVSS 8.7 High.

Data as of 7 Nov 2026, 23:24 UTC

CVSS 4.0 base score

8.7High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.5% chance of exploitation in 30 days – higher than 46% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: High
Vulnerable system integrity: None
Vulnerable system availability: None
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: High: There is a total loss of confidentiality, resulting in all information within the Vulnerable System being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 25 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 7 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
rickknowlesWinstone Servlet Container	Affected <=0.9.10	Fixed in–

AI-suggested

Until an official fix is available, restrict access to the Winstone Servlet Engine and consider running the service with least privilege to minimize potential impact. Monitor vendor channels for updates regarding a patch or official mitigation.

Description

Winstone Servlet Engine through 0.9.10 contains a path traversal vulnerability that allows unauthenticated attackers to read arbitrary files by sending HTTP GET requests with dot-dot-slash sequences that are not sanitized when serving static files from the configured webroot. Attackers can traverse outside the webroot directory using traversal-prefixed paths in a single HTTP request to read any file accessible to the servlet engine process, including sensitive system files when the service runs with elevated privileges.

Impact

Successful exploitation allows an unauthenticated attacker to read any file accessible to the Winstone Servlet Engine process, including sensitive system files if the service runs with elevated privileges. This can lead to significant confidentiality breaches. There is no indication of integrity or availability impact. No known exploits in the wild have been reported.

Summary

CVE-2026-56122 is a path traversal vulnerability in the Winstone Servlet Container (up to version 0.9.10) that permits unauthenticated remote attackers to read arbitrary files on the server. The vulnerability arises from improper sanitization of pathname inputs containing traversal sequences (../) in HTTP GET requests targeting static files. Attackers can bypass the webroot restriction and access any file readable by the servlet engine process, potentially exposing sensitive data, especially if the service operates with elevated privileges. The CVSS 4.0 base score is 8.7, reflecting high severity with network attack vector, no privileges or user interaction required, and high impact on confidentiality.

References

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