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NRDAX-T0023 - Coalesced Packet Buffer Leak

Memory amplification · P2P and gossip · no bound · active · first seen 2026-07-11

provenance: Reproduced in NullRabbit's attack-reproduction pipeline

mechanism

QUIC-LEAK / CVE-2025-54939: LSQUIC pre-handshake `packet_in` memory leak from coalesced Initial packets (CVSS 7.5 AV:N/AC:L/PR:N/UI:N/A:H, CWE-401+CWE-770; affected LSQUIC < 4.3.1, fixed 4.3.1 / OpenLiteSpeed 1.8.4 / LiteSpeed Web Server 6.3.4). An unauthenticated remote attacker floods UDP datagrams that each coalesce several QUIC v1 Initial packets - the first with a valid DCID, the rest with distinct invalid DCIDs; lsquic frees only the first coalesced packet_in per datagram and leaks (~96 B each) the rest, before any handshake, bypassing every post-handshake limit -> memory grows at ~70% of bandwidth -> OOM. PUBLIC-CVE REPLICATION captured here as the attack wire signature only (loopback UDP mock; no real lsquic endpoint stood up); the mock_leaked_* counters are a wire-side proxy for the pinned server memory.

live exposure

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

instances (1)

chainprimitivefidelityoriginreproducer (bundle)source
quic lsquic_initial_prehandshake_leak lab reverse-engineered-cve lsquic_initial_prehandshake_leak CVE-2025-54939 ↗

related (Memory amplification)

NRDAX-T0025 - Compact Block Size Integer Overflow active NRDAX-T0038 - Count Underflow Header Serving Amplification active NRDAX-T0042 - Crypto Frame Reassembly Buffer Exhaustion active NRDAX-T0046 - Decompression Bomb Resource Exhaustion active NRDAX-T0059 - Duplicate Transport Parameter Memory Leak active NRDAX-T0061 - Duplicate Tx Mempool Index Desync active NRDAX-T0071 - Ethash Verification Memory Exhaustion active NRDAX-T0095 - GraphQL Alias Query Amplification active

cite

https://nrdax.com/techniques/NRDAX-T0023

plain

NRDAX Registry. Technique NRDAX-T0023.

bibtex
@misc{nrdax_NRDAX_T0023,
  title = {Coalesced Packet Buffer Leak (NRDAX-T0023)},
  howpublished = {NRDAX Registry},
  url = {https://nrdax.com/techniques/NRDAX-T0023},
}
json (csl)
{
  "id": "nrdax-NRDAX-T0023",
  "type": "dataset",
  "title": "Coalesced Packet Buffer Leak (NRDAX-T0023)",
  "URL": "https://nrdax.com/techniques/NRDAX-T0023",
  "publisher": "NRDAX Registry"
}
badge

NRDAX-T0023 in the NRDAX registry

[![NRDAX-T0023 in the NRDAX registry](https://nrdax.com/badge/NRDAX-T0023.svg)](https://nrdax.com/techniques/NRDAX-T0023-coalesced-packet-buffer-leak)

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-T0023
Cite it (BibTeX) 
nrdax cite NRDAX-T0023 --format bibtex

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