VulnerabilityPublished 16 Mar 2026

CVE-2026-4215: FlowCI flow-core-x · Server-Side Request Forgery

Affects FlowCI flow-core-xSource CVE Database V5

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Public exploit available · CVSS 5.3 Medium.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 4.0 base score

5.3Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 11% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Base metrics

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

Threat metrics

Exploit Maturity: POC

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: Low: The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the Vulnerable System.
Vulnerable system integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact to the Vulnerable System.
Vulnerable system availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the Vulnerable System are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to 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.
Exploit Maturity: POC: Based on threat intelligence sources each of the following must apply: · Proof-of-concept is publicly available · No knowledge of reported attempts to exploit this vulnerability · No knowledge of publicly available solutions used to simplify attempts to exploit the vulnerability

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 16 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
CVSS exploit maturity: proof of concept public
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), CVSS vector, the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 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
FlowCIflow-core-x	Affected =1.23.01	Fixed in–
GitHubflowci/flow-core-x`pkg:github/flowci/flow-core-x`Other threats	Affected =1.23.01	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Given the lack of an official patch from the vendor, organizations should implement specific mitigations to reduce risk. First, restrict access to the FlowCI flow-core-x management interfaces and SMTP configuration endpoints to trusted administrators only, using network segmentation and access control lists. Monitor and log all requests to the SMTP Host Handler component for unusual or unauthorized activity indicative of SSRF attempts. Employ web application firewalls (WAFs) with rules designed to detect and block SSRF patterns targeting internal IP ranges or sensitive endpoints. If possible, disable or limit the functionality of the vulnerable Save function or SMTP Host Handler until a patch is available. Conduct internal network scanning to identify and secure any services that could be targeted via SSRF. Additionally, implement strict egress filtering on servers running FlowCI to prevent unauthorized outbound requests. Stay alert for vendor updates or community patches and plan for rapid deployment once available. Finally, educate administrators about the risks and signs of SSRF exploitation to enhance detection and response capabilities.

Description

A security flaw has been discovered in FlowCI flow-core-x up to 1.23.01. The impacted element is the function Save of the file core/src/main/java/com/flowci/core/config/service/ConfigServiceImpl.java of the component SMTP Host Handler. The manipulation results in server-side request forgery. The attack may be performed from remote. The exploit has been released to the public and may be used for attacks. The vendor was contacted early about this disclosure but did not respond in any way.

Impact

The SSRF vulnerability in FlowCI flow-core-x can have significant impacts on organizations using this software. Attackers exploiting this flaw can coerce the server to send unauthorized requests to internal or external systems, potentially bypassing firewalls and network segmentation controls. This can lead to unauthorized access to sensitive internal services, data leakage, or the ability to pivot within the network to launch further attacks. The compromise of SMTP host configurations could also disrupt email services or be used to facilitate phishing or spam campaigns. Although the CVSS score is medium, the availability of a public exploit and lack of vendor patch increase the risk. Organizations relying on FlowCI for continuous integration and deployment may face operational disruptions, data confidentiality breaches, and increased attack surface exposure. The vulnerability's exploitation could also impact the integrity of configuration data and availability of critical services.

Summary

CVE-2026-4215 is a medium-severity server-side request forgery (SSRF) vulnerability affecting FlowCI flow-core-x up to version 1.23.01. The vulnerability resides in the Save function of the SMTP Host Handler component, implemented in the ConfigServiceImpl.java file. SSRF vulnerabilities allow attackers to abuse server functionality to send crafted requests from the vulnerable server to arbitrary destinations, potentially bypassing network access controls and accessing internal services or sensitive data. The flaw can be exploited remotely without user interaction but requires low-level privileges on the system. The CVSS 4.0 vector indicates network attack vector, low attack complexity, no privileges required, no user interaction, and limited impact on confidentiality, integrity, and availability. The vendor was notified but has not issued a patch or response, and a public exploit is available, increasing the risk of exploitation. The absence of vendor mitigation and the public exploit release highlight the urgency for organizations to implement compensating controls. This vulnerability could be leveraged to perform reconnaissance, access internal resources, or facilitate further attacks within a compromised environment.

References

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