MalwarePublished 11 Aug 2026

base65-13x (npm) · Malicious Code

Affects base65-13xSource GCVE Database

Malicious package : remove base65-13x and rotate any secrets on hosts that installed it.

Data as of 12 Aug 2026, 16:10 UTC

Classification

Malicious package

Published to npm · OSV MAL-2026-13747

What to do

Remove base65-13x from every project, lockfile and image that pulls it in. Treat any host that installed it as compromised: rotate the credentials, tokens and keys it could read, from a clean machine.

Affected software

Product	Affected	Fixed in
npmbase65-13x	Affected =5.0.2	Fixed in–

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Description

--- _-= Per source details. Do not edit below this line.=-_ ## Source: amazon-inspector (59226f2c38efcc1dd5de6423edfc866125564cd726915307d7a05ca5b5f13529) base65-13x@5.0.2 impersonates cryptocoinjs/base-x, reusing its README, homepage, and API surface, but the exported decode(string) function in both src/esm/index.js (line 114) and src/cjs/index.cjs (line 116) contains a ~123KB VM-style obfuscated payload using rotated identifiers (vmR, vmr_92f1a9, vmw_4ee781) built via Object.defineProperty. The blob contains multiple references to the Function constructor and fetch, indicating dynamic code construction and outbound network I/O. Genuine base-x is roughly 50 lines of pure arithmetic with no obfuscation and no network activity. Any consumer invoking decode() on this package executes the packed VM, which dynamically constructs code with fetch capability. The destination hosts and constructed code are concealed by the obfuscation and are not statically visible. ## Source: ghsa-malware (8f16b7879f3a0b67bc7621645bf52c742af231c6e4156550ff4393f0167936ad) Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.

Impact

Any system with base65-13x@5.0.2 installed or running is considered fully compromised. The malicious code can execute dynamically constructed payloads with network access, potentially allowing attackers to control the system, exfiltrate data, or deploy further malware. All secrets and keys stored on the compromised system should be considered exposed and must be rotated immediately from a secure environment. Removing the package alone may not fully remediate the compromise due to possible persistence mechanisms.

Defensive guidance

Remove the base65-13x@5.0.2 package immediately from all affected systems. Rotate all secrets, credentials, and keys that were stored or used on the compromised systems from a separate, trusted computer. Because the package grants potential full control to attackers, conduct a thorough investigation and consider rebuilding affected systems to ensure complete remediation.

Summary

base65-13x@5.0.2 is a malicious npm package impersonating cryptocoinjs/base-x by copying its README, homepage, and API surface. Unlike the genuine package, its decode(string) function contains a large (~123KB) VM-style obfuscated payload that uses rotated identifiers and dynamic code construction via the Function constructor and fetch API. This enables outbound network communication and execution of concealed code, indicating potential remote control or data exfiltration capabilities. The obfuscation hides the destination hosts and payload details. Any invocation of decode() executes this malicious VM, compromising the host system.

References

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What to do

Affected software

Description

AI analysisMachine-generated, updated 12 Aug 2026, 00:59 UTC

Technical details

References

Community reviews