CVE-2025-59140: backlash parses collected strings with escapes. On 8 September 2025, the npm publishing account for backslash was taken over after a phishing attack. ...

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.

Metrics

CVSS 4.0

8.8/10

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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Red

EPSS Probability

0.38%

29.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-506

References

Timeline

Published: Sep 15, 2025
Last Modified: Jun 17, 2026
Status: Deferred

Frequently Asked Questions

What is CVE-2025-59140?

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.

How severe is CVE-2025-59140?

CVE-2025-59140 has a CVSS score of 8.8/10 (HIGH severity). The EPSS model estimates a 0.38% probability of exploitation in the next 30 days.

How do I fix CVE-2025-59140?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

How Strix Helps

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