VulnerabilityPublished 15 Mar 2026Updated 17 Mar 2026

CVE-2026-4186: UEditor · Cross-site Scripting

Affects UEditorSource CVE Database V5

Public exploit available · CVSS 5.1 Medium · end of life, no fix coming : replace or isolate UEditor; no fix will be released.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 4.0 base score

5.1Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 16% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: None coming – the product is end of life

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

Base metrics

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: Low
User Interaction: Passive
Vulnerable system confidentiality: None
Vulnerable system integrity: Low
Vulnerable system availability: None
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: Passive: Successful exploitation of this vulnerability requires limited interaction by the targeted user with the vulnerable system and the attacker’s payload. These interactions would be considered involuntary and do not require that the user actively subvert protections built into the vulnerable system.
Vulnerable system confidentiality: None: There is no loss of confidentiality within 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: 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.
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 15 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

No fix will be released: UEditor is end of life. Replace it, or isolate it from untrusted networks until you can.

Affected software

Product	Affected	Fixed in
UEditor	Affected =1.4.3.0 =1.4.3.1 =1.4.3.2	Fixed in–

AI-suggested

Given the absence of official patches due to discontinued support, organizations should prioritize upgrading to a maintained and patched version of UEditor or switch to alternative editors with active security support. If upgrading is not immediately feasible, implement strict input validation and output encoding on the server side to sanitize the 'callback' parameter, ensuring it only accepts safe, predefined callback names or patterns. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers. Additionally, monitor web server logs for suspicious requests targeting the vulnerable endpoint and educate users about phishing risks that could lead to exploitation. Web application firewalls (WAFs) can be configured to detect and block malicious payloads targeting the callback parameter. Regular security assessments and penetration testing should verify the effectiveness of these mitigations. Finally, consider isolating or disabling the vulnerable uploadimage functionality if it is not essential to reduce the attack surface.

Description

A vulnerability was determined in UEditor up to 1.4.3.2. This issue affects some unknown processing of the file php/controller.php?action=uploadimage of the component JSONP Callback Handler. This manipulation of the argument callback causes cross site scripting. The attack can be initiated remotely. The exploit has been publicly disclosed and may be utilized. The vendor was contacted early about this disclosure but did not respond in any way. This vulnerability only affects products that are no longer supported by the maintainer.

Impact

The primary impact of CVE-2026-4186 is the compromise of confidentiality and integrity through cross-site scripting attacks. Attackers can execute arbitrary scripts in the context of affected web applications, potentially stealing user credentials, session tokens, or performing unauthorized actions on behalf of users. This can lead to account takeover, data leakage, or further exploitation within the victim's environment. Since the vulnerability is in a widely used web editor component, any web application embedding vulnerable UEditor versions is at risk, especially those handling sensitive user data or authentication. The lack of vendor support and patches increases the risk of prolonged exposure. Organizations relying on these versions may face reputational damage, regulatory compliance issues, and operational disruptions if exploited. The requirement for user interaction somewhat limits automated exploitation but does not eliminate risk, especially in phishing or social engineering scenarios.

Summary

CVE-2026-4186 identifies a cross-site scripting vulnerability in UEditor, an open-source rich text web editor widely used in web applications. The flaw exists in versions 1.4.3.0 through 1.4.3.2 within the JSONP callback handler implemented in the php/controller.php?action=uploadimage endpoint. Specifically, the 'callback' parameter is not properly sanitized or validated, allowing an attacker to inject arbitrary JavaScript code. When a victim accesses a crafted URL containing malicious payloads in the callback parameter, the injected script executes in the victim's browser context. This can lead to theft of session cookies, defacement, or redirection to malicious sites. The vulnerability is remotely exploitable without authentication but requires user interaction to trigger. The vendor has discontinued support for these versions and has not issued a patch or response to the disclosure. The CVSS 4.0 base score is 5.1, reflecting medium severity due to the ease of exploitation and limited impact scope. No known active exploitation has been reported, but public disclosure increases the risk of future attacks. The lack of vendor response and patch availability means organizations must rely on alternative mitigations or upgrade to supported software versions.

References

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