NRDAX-T0291 - Subscription Permit Exhaustion

Connection exhaustion · RPC and public API · mis-scoped bound · active · first seen 2026-07-03

provenance: Reproduced in NullRabbit's attack-reproduction pipeline

mechanism

C04 (COSMOS_SUBSCRIBE_PERCONN_CAP): CometBFT rpc/core/events.go:27 caps NumClients>=MaxSubscriptionClients(100) but clientID=RemoteAddr(ip:PORT) → each TCP conn gets an independent per-client cap → subscription multiplication across many connections from one IP

live exposure

No exposure data. Slashr ↗ has no risk signal mapped to this technique yet — absence of data is not absence of exposure.

instances (3)

chain	primitive	fidelity	origin	reproducer (bundle)	source
cosmos	cosmos_subscribe_perconn_multiply	lab	NullRabbit Labs	cosmos_subscribe_perconn_multiply	-
sui	sui_p01_p06_subscribe_filter_exhaustion	lab	NullRabbit Labs	sui_p01_p06_subscribe_filter_exhaustion	github.com ↗
sui	sui_subscription_permit_leak	lab	NullRabbit Labs	sui_subscription_permit_leak	-

related (Connection exhaustion)

NRDAX-T0041 - Cross-Chain Peer Pool Pollution active NRDAX-T0064 - Endpoint Concurrency Cap Exhaustion active NRDAX-T0099 - Half-Open Handshake Slowloris active NRDAX-T0214 - Protocol Message Flood Unbounded Goroutine active NRDAX-T0225 - QUIC Control Frame Flood active NRDAX-T0246 - Rate-Limit Key Confusion active NRDAX-T0261 - RPC Request Flood active NRDAX-T0320 - Unbounded Connection Flood active

cite

https://nrdax.com/techniques/NRDAX-T0291

plain

NRDAX Registry. Technique NRDAX-T0291.

bibtex

@misc{nrdax_NRDAX_T0291,
  title = {Subscription Permit Exhaustion (NRDAX-T0291)},
  howpublished = {NRDAX Registry},
  url = {https://nrdax.com/techniques/NRDAX-T0291},
}

json (csl)

{
  "id": "nrdax-NRDAX-T0291",
  "type": "dataset",
  "title": "Subscription Permit Exhaustion (NRDAX-T0291)",
  "URL": "https://nrdax.com/techniques/NRDAX-T0291",
  "publisher": "NRDAX Registry"
}

badge

[![NRDAX-T0291 in the NRDAX registry](https://nrdax.com/badge/NRDAX-T0291.svg)](https://nrdax.com/techniques/NRDAX-T0291-subscription-permit-exhaustion)

use from the CLI

Retrieve or cite this technique from a script or the terminal with the NRDAX Python library & CLI.

Retrieve this technique

nrdax get NRDAX-T0291

Cite it (BibTeX)

nrdax cite NRDAX-T0291 --format bibtex

CLI guide → GitHub ↗