VulnerabilityPublished 11 Mar 2026Updated 12 Mar 2026

CVE-2026-3951: LockerProject Locker · Cross-site Scripting

Affects LockerProject LockerSource CVE Database V5

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Public exploit available · CVSS 5.3 Medium.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 4.0 base score

5.3Medium

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: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: None
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: 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: 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 11 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 30 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
LockerProjectLocker	Affected =0.0.0 =0.0.1 =0.1.0	Fixed in–
GitHublockerproject/Locker`pkg:github/lockerproject/Locker`Other threats	Affected =0.0.0 =0.0.1 =0.1.0	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 absence of an official patch, organizations should implement multiple layers of mitigation to reduce risk. First, apply strict input validation and output encoding on all user-supplied data, especially the ID parameter processed by the authIsAwesome function, to neutralize malicious scripts. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers. Educate users to avoid clicking suspicious links and to report unexpected behavior. Monitor web application logs for unusual input patterns targeting the vulnerable function. If feasible, isolate or disable the affected component until a patch is released. Consider deploying web application firewalls (WAFs) with custom rules to detect and block exploitation attempts targeting the known vulnerability signature. Maintain up-to-date backups and incident response plans to quickly recover from potential compromises. Engage with LockerProject for updates and patches, and plan for timely software upgrades once available.

Description

CVE-2026-3951 is a medium severity cross-site scripting (XSS) vulnerability affecting LockerProject Locker versions 0.0.0, 0.0.1, and 0.1.0. The flaw exists in the authIsAwesome function within the Error Response Handler component, specifically in the file registry.js. An attacker can remotely manipulate the ID argument to inject malicious scripts, potentially leading to user session hijacking or phishing attacks.

Impact

The primary impact of CVE-2026-3951 is the compromise of confidentiality and integrity of user sessions within applications using the vulnerable LockerProject Locker versions. Successful exploitation can lead to theft of sensitive information such as authentication tokens, cookies, or personal data, enabling attackers to impersonate users or conduct phishing attacks. While the vulnerability does not directly affect system availability, the resulting compromise can lead to broader security incidents including unauthorized access and data breaches. Organizations relying on affected versions may face reputational damage, regulatory penalties, and operational disruptions if exploited. The public availability of exploit code increases the likelihood of opportunistic attacks, especially against less security-aware or unpatched environments. The medium severity rating reflects the moderate impact balanced against the requirement for user interaction and the absence of privilege escalation.

References

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