claims-use-callback-once (npm) · Malicious Code
Affects claims-use-callback-onceSource GCVE Database
Malicious package : remove claims-use-callback-once and rotate any secrets on hosts that installed it.
Data as of 5 Aug 2026, 16:18 UTC
Malicious package
Published to npm · OSV MAL-2026-12647
What to do
Remove claims-use-callback-once 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 |
|---|---|---|
| npmclaims-use-callback-once | Affected
| Fixed in– |
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Description
The npm package claims-use-callback-once version 35.6.7 contains malicious code that downloads and executes a payload from multiple hardcoded Cloudflare Workers hosts and a DNS TXT base64 fallback domain. The payload is saved under deceptive Microsoft-diagnostics-style filenames in temporary directories, given executable permissions, and executed detached from the main process. The package masquerades as a callback utility but includes no legitimate functionality and uses obfuscation techniques to evade static analysis. A parallel dropper implementation is disguised as an 'Analytics SDK'.