base65-11x (npm) · Malicious Code
Affects base65-11xSource GCVE Database
Malicious package : remove base65-11x and rotate any secrets on hosts that installed it.
Data as of 12 Aug 2026, 16:10 UTC
Malicious package
Published to npm · OSV MAL-2026-13745
What to do
Remove base65-11x 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 |
|---|---|---|
| npmbase65-11x | Affected
| Fixed in– |
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Description
--- _-= Per source details. Do not edit below this line.=-_ ## Source: amazon-inspector (14cc9506a804a2663d0cde1c610fa8cba5733e6797652b6365569ada5ef3901d) base65-11x is a name-lookalike of the widely used base-x encoder. Both entrypoints (src/cjs/index.cjs and src/esm/index.js, ~127KB each vs. ~4KB for real base-x) contain the legitimate base-x source followed by a ~123KB single-line obfuscated payload wrapped in a custom-VM IIFE (identifiers vmN, vmA_ab9191, vmU_d6a896; Object.defineProperty-based dispatch on a global slot). The payload sits at module top level, so it executes automatically whenever a consumer require()s or import()s the package. A pure base-encoding utility has no functional need for runtime-VM-packed code on load, and the payload is duplicated across CJS and ESM entrypoints to ensure execution regardless of module system. The specific payload behavior is concealed inside the VM interpreter and cannot be recovered without executing it. ## Source: ghsa-malware (672a03fa0011f4095fdff19eaa7e65ffa8ae44f34e673a707488903c5b6eab67) 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.