CVE Intelligence
High Injection exploit reference

CVE-2025-58056 — Netty is vulnerable to request smuggling due to incorrect parsing of chunk extensions

Netty is an asynchronous event-driven network application framework for development of maintainable high performance protocol servers and clients. In versions 4.1.124.Final, and 4.2.0.Alpha3 through 4.2.4.Final, Netty incorrectly accepts standalone newline characters (LF) as a chunk-size line terminator, regardless of a preceding carriage return (CR), instead of requiring CRLF per HTTP/1.1 standards. When combined with reverse proxies that parse LF differently (treating it as part of the chunk extension), attackers can craft requests that the proxy sees as one request but Netty processes as two, enabling request smuggling attacks. This is fixed in versions 4.1.125.Final and 4.2.5.Final.

Published Sep 3, 2025 · Updated Oct 19, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: GitHub_M

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.7% (30-day exploitation probability)+8
  • Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.71%
ahead of 53% of scored CVEs · Oct 19, 2026
Affects
Netty
Netty and 1 more
CVSS base
7.5
High · 3 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
No
can an attacker script the kill-chain steps
Technical impact
Partial
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

  • Documented patch — github.com (NIST National Vulnerability Database)
  • Documented patch — github.com (NIST National Vulnerability Database)
  • Maven Io.netty:netty-codec-http: fixed in version 4.1.125.Final — github.com (GitHub Security Advisories)
  • Maven Io.netty:netty-codec-http: fixed in version 4.2.5.Final — github.com (GitHub Security Advisories)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Netty Netty, Maven Io.netty:netty-codec-http).
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. Apply the fixed version or the patch documented under Remediation.
  4. Search available logs for exploit probes matching the vulnerability class (injection), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Netty Netty < 4.1.125≥ 4.2.0 and < 4.2.5 Vulnerable NIST National Vulnerability Database
Netty Netty version >= 4.2.0.Alpha3, < 4.2.5.Finalversion <= 4.1.124.Final, < 4.1.125.Final Vulnerable CVE Program (cve.org) e CISA ADP
Maven Io.netty:netty-codec-http < 4.1.125.Final≥ 4.2.0.Alpha1 and < 4.2.5.Final Vulnerable GitHub Security Advisories

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
2.9 CVSS 4.0 Low — — security-advisories@github.com via NIST National Vulnerability Database
2.9 CVSS 4.0 Low — — GitHub_M via CVE Program (cve.org) e CISA ADP
7.5 CVSS 3.1 High 3.9 3.6 nvd@nist.gov via NIST National Vulnerability Database
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-444 · HTTP Request Smuggling

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
  • Look for parameters with command/query metacharacters and unexpected child processes of the service.
web/proxy/WAF logsnetwork IDS/IPSapplication logsendpoint telemetry (EDR)

Timeline

What happened to this CVE, newest first.

  • 2026
  • Fix documented
    Oct 19, 2026 · GitHub Security Advisories
  • Affected products added · maven/io.netty:netty-codec-http
    Oct 19, 2026 · GitHub Security Advisories
  • Affected products added · netty/netty
    Oct 19, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 19, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 19, 2026
  • Fix documented
    Oct 19, 2026 · NIST National Vulnerability Database
  • Affected products added · netty/netty
    Oct 19, 2026 · NIST National Vulnerability Database
  • CVSS changed · 7.5
    Oct 19, 2026 · NIST National Vulnerability Database
  • Source status changed · → Analyzed
    Oct 19, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 19, 2026 · Alertas do Telegram
  • 2025
  • CVE published
    Sep 3, 2025 · GitHub_M

Source activity

Repeated readings are counted rather than listed.

  • 2× References added · Oct 19, 2026 – Oct 19, 2026
  • 1× Official description updated · Oct 19, 2026 – Oct 19, 2026

References

10 on the record

Elsewhere on this site

Netty
every CVE for this vendor
Injection
same class
CWE-444
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-100666 Netty 4.2.0 through 4.2.16 Response Desynchronization via HttpServerCodec 23d
  • CVE-2026-100661 Netty HTTP/3 QPACK Prefixed Integer DoS via Unbounded Accumulation 23d
  • CVE-2026-100662 Netty HTTP/3 QPACK encoder-stream unbounded memory exhaustion DoS 23d
  • CVE-2026-100663 Netty HTTP/1 CONNECT authority-form mistranslated to malformed HTTP/3 23d
  • CVE-2026-100665 Netty 4.2.11 through 4.2.17 QUIC Hostname Verification Bypass 23d
  • CVE-2026-100664 Netty 4.2.2 through 4.2.17 HTTP/1 Host Header Authority Confusion 23d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2025-58056 is "Netty is vulnerable to request smuggling due to incorrect parsing of chunk extensions", rated High. It affects Netty (Netty); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.5 describes technical severity. EPSS 0.71% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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