VulnerabilityPublished 15 Sep 2025

CVE-2025-59140: Qix- node-backslash · Embedded Malicious Code

Affects Qix- node-backslashSource CVE Database V5

Not known to be exploited · CVSS 8.8 High · fixed in 0.2.2 : patch Qix- node-backslash soon.

Data as of 26 Oct 2026, 11:42 UTC

CVSS 4.0 base score

8.8High

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

EPSS: 0.4% chance of exploitation in 30 days – higher than 34% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 0.2.2

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

Base metrics

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

Threat metrics

Exploit Maturity: Attacked

Supplemental metrics

Provider Urgency: Red

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: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the vulnerable system. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence 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: Attacked: Based on threat intelligence sources either of the following must apply: · Attacks targeting this vulnerability (attempted or successful) have been reported · Solutions to simplify attempts to exploit the vulnerability are publicly or privately available (such as exploit toolkits)
Provider Urgency: Red: Provider has assessed the impact of this vulnerability as having the highest urgency.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 15 Sep 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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
Qix- node-backslash	Affected =0.2.1	Fixed in–

AI-suggested

Immediately upgrade all instances of node-backslash to version 0.2.2 or later.
Completely remove the node_modules directory and any lock files (package-lock.json or yarn.lock) to ensure no residual compromised code remains.
Clear all package manager caches globally (npm cache clean --force) and locally, including private registries and mirrors, to prevent inadvertent reinstallation of the malicious version.
Rebuild all browser bundles from scratch using clean environments to eliminate embedded malicious payloads.
Audit all web applications and browser-based tools that use node-backslash, especially those handling cryptocurrency wallets or transactions, to verify no malicious code persists.
Monitor network traffic for suspicious redirection attempts or unauthorized cryptocurrency transactions.
Educate development and DevOps teams about phishing risks to prevent future account compromises.
Implement strict access controls and multi-factor authentication on npm publishing accounts and private registries.
Employ supply chain security tools that verify package integrity and provenance before deployment.
For organizations running private npm registries or mirrors, purge all cached versions of node-backslash 0.2.1 and enforce policies to prevent use of compromised versions.

Description

backlash parses collected strings with escapes. On 8 September 2025, the npm publishing account for backslash was taken over after a phishing attack. Version 0.2.1 was published, functionally identical to the previous patch version, but with a malware payload added attempting to redirect cryptocurrency transactions to the attacker's own addresses from within browser environments. Local environments, server environments, command line applications, etc.are not affected. If the package was used in a browser context (e.g.a direct <script> inclusion, or via a bundling tool such as Babel, Rollup, Vite, Next.js, etc.) there is a chance the malware still exists and such bundles will need to be rebuilt. The malware seemingly only targets cryptocurrency transactions and wallets such as MetaMask.npm removed the offending package from the registry over the course of the day on 8 September, preventing further downloads from npm proper. On 13 September, the package owner published new patch versions to help cache-bust those using private registries who might still have the compromised version cached. Users should upgrade to the latest patch version, completely remove their node_modules directory, clean their package manager's global cache, and rebuild any browser bundles from scratch. Those operating private registries or registry mirrors should purge the offending versions from any caches. This issues is resolved in 0.2.2.

Impact

For European organizations, the impact of this vulnerability is significant, especially for those involved in cryptocurrency transactions or developing web applications that integrate cryptocurrency wallet interactions within browsers. The malicious code compromises transaction integrity by redirecting funds to attacker-controlled wallets, potentially leading to direct financial losses. Since the attack targets client-side environments, any web application or service that bundles the compromised package for browser use is at risk. This could affect fintech companies, cryptocurrency exchanges, blockchain service providers, and any enterprise offering browser-based crypto wallet integrations. The reputational damage and regulatory implications under GDPR and other European data protection laws could be severe if customer funds are stolen or if the breach leads to data exposure. Additionally, organizations relying on private npm registries or mirrors may unknowingly continue to distribute the compromised package, extending the threat's reach. The swift removal of the package from the public npm registry mitigates further spread, but the persistence of cached versions in private environments remains a concern.

Summary

CVE-2025-59140 is a high-severity supply chain vulnerability affecting the npm package 'node-backslash' maintained by the Qix- project. The vulnerability arises from a malicious code injection in version 0.2.1 of the package, which was published after the npm publishing account was compromised via a phishing attack on September 8, 2025. The malicious payload embedded in this version targets browser environments specifically, attempting to intercept and redirect cryptocurrency transactions to attacker-controlled addresses. This attack vector exploits the package's use in client-side JavaScript contexts, such as direct script inclusion or through bundling tools like Babel, Rollup, Vite, or Next.js. Importantly, server-side, local, or command-line environments using this package are not affected. The malware focuses on cryptocurrency wallets such as MetaMask, aiming to hijack transaction flows within the browser. The compromised package was promptly removed from the npm registry on the same day, and subsequent patch version 0.2.2 was released on September 13 to remediate the issue and assist users in cache busting. The CVSS 4.0 score of 8.8 reflects the high impact and ease of exploitation without authentication or user interaction, with a significant impact on the integrity of cryptocurrency transactions. Organizations using this package in browser contexts must ensure they upgrade to the fixed version, clear caches, remove node_modules directories, and rebuild all browser bundles to eliminate the malicious code. Private registries and mirrors must also purge cached compromised versions to prevent further exposure.

CWE-506Embedded Malicious Code (opens in a new tab)
Class weaknessOWASP Top 10 A08:2025: Software or Data Integrity Failures (opens in a new tab)
The product contains code that appears to be malicious in nature.
Implementation · Operation
Remove the malicious code and start an effort to ensure that no more malicious code exists. This may require a detailed review of all code, as it is possible to hide a serious attack in only one or two lines of code.
OWASP Cheat Sheets
Software Supply Chain Security (opens in a new tab)
Infrastructure as Code (opens in a new tab)
Attack patterns
Infected Software (opens in a new tab)
Embed Virus into DLL (opens in a new tab)
Hiding Malicious Data or Code within Files (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 23 Sep 2025, 01:06 UTC

WeaknessesCWE-506

Technical details

References

Community reviews

Related threats