A missing bounds check in the binary decoder in lib0, versions 0.2.1-0.2.117 and earlier and…

Why it is Amber

• CVSS 8.6 high
• Remotely exploitable without logging in

References

• https://github.com/dmonad/lib0/commit/425f28dc82c8df1b6f7e1ab20ea1a0a15a3c355f
• https://github.com/dmonad/lib0/commit/c4c9db0b41346a33aff31a51f1f09c3a17757f10
• https://github.com/dmonad/lib0/security/advisories/GHSA-r5c8-rf4w-qrq8
• https://github.com/dmonad/lib0/security/advisories/GHSA-r5c8-rf4w-qrq8

Original description

A missing bounds check in the binary decoder in lib0, versions 0.2.1-0.2.117 and earlier and 1.0.0-rc.32 and earlier, lets any unauthenticated remote peer read adjacent process memory and receive it back. `readUint8Array` never compares the wire-supplied length against the decoder's own view, so one over-long length prefix returns whatever the host process allocated next: other tenants' document content, personal data, and live bearer session tokens**, recovered in full and at will. An attacker who can supply bytes to a lib0 decoder which means any peer that can open a socket, including before authentication reads adjacent process memory and, where the consumer echoes, stores or re-serves the decoded value, receives it back. This is patched in version 0.2.118 and 1.0.0-rc.33.