CVE-2026-42582

Status: AnalyzedHigh (7.5)—

Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final, when decoding header blocks, the non-Huffman branch of io.netty.handler.codec.http3.QpackDecoder#decodeHuffmanEncodedLiteral may execute new byte[length] for a string literal before verifying that length bytes are actually present in the compressed field section. The wire encoding allows a very large length to be expressed in few bytes. There is no check that length <= in.readableBytes() before new byte[length]. This vulnerability is fixed in 4.2.13.Final.

CVSS

Version: 3.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Base score: 7.5

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days: 0.49%
Percentile among all scored CVEs: 40
Score date: 10/6/2026

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

🎯 ATT&CK techniques

How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.

ExploitationT1190 Exploit Public-Facing Applicationinitial access90 %
Primary impactT1499.004 Application or System Exploitationimpact85 %
Secondary impactT1499 Endpoint Denial of Serviceimpact75 %

Vulnerabilidad de negación de servicio en decodificador HTTP/3 remoto (AV:N, PR:N, UI:N) explotable sin autenticación. Asignación de memoria masiva sin validación (CWE-770, CWE-789) causa agotamiento de recursos y caída.

Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.

🛡️ ATT&CK mitigations that cover these techniques

Filter Network Traffic Vulnerability Scanning Privileged Account Management Network Segmentation Limit Access to Resource Over Network Application Isolation and Sandboxing

Affected technologies (1)

Netty — Netty

CWEs

CWE-770, CWE-789

References

Raw JSON (NVD)

Show

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