tcb-web-header (npm) · Malicious Code
Affects tcb-web-headerSource GCVE Database
Malicious package : remove tcb-web-header and rotate any secrets on hosts that installed it.
Data as of 6 Aug 2026, 18:24 UTC
Malicious package
Published to npm · OSV MAL-2026-12476
What to do
Remove tcb-web-header 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 |
|---|---|---|
| npmtcb-web-header | Affected
| Fixed in– |
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Description
--- _-= Per source details. Do not edit below this line.=-_ ## Source: amazon-inspector (115bda849ee7aff33e1ccc649f492e892e31243bfb026eea8048c158c885bdf0) On require() of tcb-web-header, _platform.js selects an OS/arch-specific endpoint, downloads a binary from Cloudflare workers.dev hosts whose names are reconstructed at runtime by joining split string fragments (e.g. oob-worker.cf99-9b.3.workers.dev, oob-worker.cf100-416.workers.dev, oob-worker.cf101-adf.workers.dev), writes the payload to /var/tmp or %TEMP% under a deceptive name (dotnet_diag_<tag>.exe on Windows,.cache_<tag> on Unix), fs.chmodSync to 0o755, and spawns it detached via /bin/sh -c "<path> &" or cmd.exe /c start /b. A base64-encoded chunked DNS TXT retrieval channel over c.<domain>/N.<domain> under tin.dl.well1.site, tina.dl.well1.site, ldr.dl.well1.site, and win.dl.well1.site serves as a covert fallback transport when HTTPS is blocked. The package's declared purpose is a web header helper and there is no build/native-addon rationale for downloading and executing an unverified binary at import time; destination hosts are attacker-controlled, string-reassembled to defeat static scanners, and a token-gated DISABLE_TELEMETRY flag is used as a cover story. ## Source: ghsa-malware (77922987a2e7e78e43a4eda61cd08125e62f1bcb4d74fbe3c39abcb5c63be148) 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.