VulnerabilityPublished 21 Mar 2026Updated 23 Mar 2026

CVE-2026-4528: trueleaf ApiFlow · Server-Side Request Forgery

Affects trueleaf ApiFlowSource CVE Database V5

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Public exploit available · CVSS 6.9 Medium.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 4.0 base score

6.9Medium

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 23% 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: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: None
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: 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: 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 21 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
trueleafApiFlow	Affected =0.9.7	Fixed in–
npmtrueleaf/apiflow`pkg:npm/trueleaf/apiflow`Other threats	Affected =0.9.7	Fixed in–

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

AI-suggested

To mitigate CVE-2026-4528, organizations should first upgrade ApiFlow to a version where the vulnerability is patched once available. In the absence of an official patch, implement strict allowlists for URLs that the ApiFlow server can access, limiting outbound requests to trusted domains only. Employ network-level controls such as firewall rules or proxy restrictions to prevent the server from reaching internal or sensitive endpoints. Review and harden the validateUrlSecurity function or disable proxy features if not required. Monitor logs for unusual outbound requests that may indicate exploitation attempts. Additionally, conduct internal penetration testing to identify potential SSRF attack paths. Educate developers and administrators about SSRF risks and ensure secure coding practices for URL validation. Finally, keep abreast of vendor advisories and apply patches promptly once released.

Description

CVE-2026-4528 is a server-side request forgery (SSRF) vulnerability found in trueleaf ApiFlow version 0.9.7. The flaw exists in the validateUrlSecurity function within the URL Validation Handler, allowing attackers to manipulate URL validation and cause SSRF. This vulnerability can be exploited remotely without authentication or user interaction. The CVSS 4.0 base score is 6.9, indicating a medium severity level. Although no known exploits are currently in the wild, the vulnerability has been publicly disclosed, increasing the risk of exploitation. The impact includes unauthorized internal network access, potential data leakage, and interaction with internal services.

Impact

The SSRF vulnerability in ApiFlow 0.9.7 can have significant consequences for organizations. Attackers exploiting this flaw can cause the server to send crafted requests to internal services that are otherwise inaccessible externally, potentially exposing sensitive data or internal APIs. This can lead to unauthorized information disclosure, bypassing network segmentation, and facilitating further attacks such as lateral movement or privilege escalation. The vulnerability may also be used to scan internal networks or interact with cloud metadata services, increasing the risk of credential theft. Since the exploit requires no authentication or user interaction, any exposed ApiFlow 0.9.7 instance is at risk. The medium severity rating reflects a balance between the ease of exploitation and the potential impact, but organizations with critical internal services behind ApiFlow proxies should treat this vulnerability seriously to prevent compromise.

References

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