LiveActive security incident?Get immediate response
CVE Record

CVE-2026-42579: Netty: DNS Codec Input Validation Bypass in Netty (Encoder + Decoder)

Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, Netty's DNS codec does not enforce RFC 1035 domain name constraints during either encoding or decoding. This creates a bidirectional attack surface: malicious DNS responses can exploit the decoder, and user-influenced hostnames can exploit the encoder. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.

HighCVSS 7.5Not KEV-listedUpdated
Discuss exposureBack to CVEs
Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

Netty applications using affected DNS codec versions may mishandle invalid domain names. The issue can be triggered through malicious DNS responses or hostnames influenced by users. The main stated impact is integrity, not data theft or service outage. Fixed Netty releases are available.

Executive priority

Treat as a high-priority dependency remediation item. It is not currently supported by the provided sources as actively exploited, but the low-complexity network attack path and available fixes justify prompt patching in exposed or critical Java services.

Technical view

Before 4.2.13.Final and 4.1.133.Final, Netty DNS codec encoding and decoding did not enforce RFC 1035 domain name constraints. This creates decoder exposure from malicious DNS responses and encoder exposure from user-influenced hostnames. CVSS 3.1 is 7.5 with network attack vector and high integrity impact.

Likely exposure

Exposure is most likely in Java services, frameworks, or products that directly or transitively include affected Netty versions and use Netty DNS resolution or DNS codec behavior. Red Hat has related advisories, so packaged enterprise products should be checked against vendor-specific status.

Exploitation context

The provided bundle does not show CISA KEV listing or cited evidence of active exploitation. The vulnerability is network-reachable, requires no privileges or user interaction, and affects both decoding DNS responses and encoding user-influenced hostnames.

Researcher notes

Focus triage on code paths where untrusted DNS responses or user-controlled hostnames reach Netty DNS codec operations. Avoid assuming all Netty users are exploitable; exposure depends on version, packaging, and DNS codec use. The source bundle does not provide proof-of-concept details.

Mitigation direction

  • Upgrade Netty to 4.2.13.Final or 4.1.133.Final.
  • Inventory direct and transitive Netty dependencies across Java applications.
  • Check Red Hat errata for product-specific fixed packages.
  • Validate user-influenced hostnames against RFC 1035 constraints.
  • Prioritize externally exposed services and DNS-heavy workloads first.

Validation and detection

  • Review SBOMs, lockfiles, and build manifests for affected Netty versions.
  • Confirm runtime artifacts do not bundle vulnerable Netty releases.
  • Identify services using Netty DNS resolver or codec functionality.
  • Check vendor advisories for Red Hat product applicability.
  • Verify patched versions are deployed, not only declared in source.
Prepared
Confidence
high
Sources
12

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-1286: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cwe · low confidence lookup

CWE-20: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cwe · low confidence lookup

CWE-400: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cwe · low confidence lookup

CWE-626: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2026-42579 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
5Timeline events
2ADP providers
11Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: pocAutomatable: yesTechnical Impact: partial

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N3.93.6GitHub_M
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N3.93.6redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2026-42579Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPnetty: Netty: High integrity impact due to improper DNS domain name constraint enforcement
other:Red Hat severity ratingcvssV3_1
  • 2026-05-13T19:01:25.062Z: Reported to Red Hat.
  • 2026-05-13T18:01:52.500Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
nettynetty>= 4.2.0.Alpha1, < 4.2.13.Final, < 4.1.133.FinalListed
Weakness

CWE details

CWE-1286CWE-20CWE-400CWE-626

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.