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CVE Record

CVE-2026-48043: netty-codec-http2: ByteBuf Reference-Count Leak in DelegatingDecompressorFrameListener Leads to Memory Exhaustion

Netty is a network application framework for development of protocol servers and clients. In netty-codec-http2 prior to versions 4.1.135.Final and 4.2.15.Final, the `DelegatingDecompressorFrameListener` class orchestrates HTTP/2 decompression by embedding a per-stream `EmbeddedChannel` that runs the appropriate decompression codec (gzip, deflate, zstd) and forwards decompressed chunks to a wrapped listener. Each decompressed chunk is a pooled `ByteBuf` handed to an anonymous `ChannelInboundHandlerAdapter` tail handler, which becomes the sole owner responsible for releasing it. A remote peer could send frames that would result in the flow-controller throwing and so trigger a resource leak which at the end might take down the whole JVM due OOME. Versions 4.1.135.Final and 4.2.15.Final patch the issue.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2026-48043 is a denial-of-service flaw in Netty’s HTTP/2 decompression handling. A remote peer can cause memory buffers to leak until the Java process runs out of memory, potentially taking down the service. The issue is patched in Netty 4.1.135.Final and 4.2.15.Final.

Executive priority

Treat as high priority for internet-facing HTTP/2 Java services because exploitation can interrupt availability without authentication. Patch exposed systems first, then validate transitive dependencies and vendor-packaged Netty across internal services.

Technical view

In netty-codec-http2, DelegatingDecompressorFrameListener uses per-stream EmbeddedChannel decompression for gzip, deflate, and zstd. Certain frames can make the flow controller throw while decompressed pooled ByteBuf chunks are not released, creating a reference-count leak. Repeated triggering can exhaust JVM memory and cause OOME.

Likely exposure

Exposure is likely where Java services directly or transitively use vulnerable netty-codec-http2 versions and accept HTTP/2 traffic with decompression. Affected ranges are below 4.1.135.Final and 4.2.0.Final through before 4.2.15.Final. Red Hat advisories indicate downstream product assessment and fixes exist for some packaged products.

Exploitation context

The source bundle describes remote, unauthenticated network reachability with low attack complexity and availability-only impact. It does not cite public exploit code or confirmed active exploitation. KEV status is false, so active exploitation should not be claimed from these sources.

Researcher notes

The strongest evidence is the upstream GitHub advisory and CVE metadata. The vulnerability is a ByteBuf lifecycle failure during HTTP/2 decompression error handling, mapped to CWE-400, CWE-401, and CWE-772. The bundle does not provide a proof of concept or detailed affected downstream inventory.

Mitigation direction

  • Upgrade netty-codec-http2 to 4.1.135.Final, 4.2.15.Final, or later supported builds.
  • Apply relevant Red Hat errata for products that package or embed Netty.
  • Prioritize externally reachable HTTP/2 services and Java gateways using vulnerable Netty versions.
  • Check vendor guidance for backports, product-specific fixes, or configuration mitigations.

Validation and detection

  • Inventory SBOMs and dependency trees for vulnerable netty-codec-http2 versions.
  • Check shaded jars, containers, and bundled application artifacts for embedded Netty copies.
  • Confirm production HTTP/2 endpoints using Netty are patched or otherwise vendor-mitigated.
  • Monitor JVM memory, Netty leak detection, and availability signals during remediation.
Prepared
Confidence
high
Sources
11

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-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-401: 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-772: 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-2026-48043 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:N/A:H

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
13Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: 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:N/A:H3.93.6redhat-SADP
5.3CVSS 3.1MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L3.91.4GitHub_M

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2026-48043Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

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-codec-http2: netty-codec-http2: Denial of Service due to resource leak
other:Red Hat severity ratingcvssV3_1
  • 2026-06-12T16:02:56.371Z: Reported to Red Hat.
  • 2026-06-12T14:39:52.498Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
nettynetty>= 4.2.0.Final, < 4.2.15.Final, < 4.1.135.FinalListed
Weakness

CWE details

CWE-400CWE-401CWE-772

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