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TI-2026-64817 Aliases CVE-2026-100661GHSA-7m86-g9j9-26xf

Netty HTTP/3 QPACK Prefixed Integer DoS via Unbounded Accumulation

Priority MEDIUM 44CWE-400Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Partial Red Hat: 1 without a fix

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-400.

Summary

Netty's HTTP/3 codec (io.netty:netty-codec-http3) versions 4.2.0.Final through 4.2.17.Final contain a denial-of-service vulnerability in the QPACK prefixed-integer decoder (QpackUtil.decodePrefixedInteger), which does not bound the number of continuation bytes it will process. A remote, unauthenticated peer can open a QPACK unidirectional stream (type 0x02 encoder or 0x03 decoder) and send a first byte with all prefix bits set (e.g. 0xFF for a 7-bit prefix or 0x3F for a 5-bit prefix) followed by an endless run of 0x80 continuation bytes. The decoder returns -1 ('need more bytes'), so callers never consume the input, the ByteToMessageDecoder cumulator grows without bound, and each decode() invocation re-scans the whole accumulated buffer, yielding O(N^2) CPU cost. The result is unbounded per-connection heap growth (OutOfMemoryError) and event-loop CPU starvation, reachable in every configuration. Fixed in 4.2.18.Final.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00344 28th percentileScored 2026-11-07
Fix Partial netty (netty): 4.2.18.FinalRed Hat: 1 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
nettynetty4.2.0.Final to before 4.2.18.Final4.2.18.FinalPatch availableCNA
  • netty Vendornetty Affected 4.2.0.Final to before 4.2.18.Final Fixed in 4.2.18.Final Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*——netty
  • cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:* Versions — — ·netty

Remediation

  • Fix · CNA netty (netty) Fixed in 4.2.18.Final

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    netty 4.2.18.Final

    7 records Highest priority Priority HIGH 4 HIGH, 2 MEDIUM, 1 LOW

    Other records, highest priority first

    • TI-2026-64821 Netty 4.2.11 through 4.2.17 QUIC Hostname Verification BypassPriority HIGH 77
    • TI-2026-64818 Netty HTTP/3 QPACK encoder-stream unbounded memory exhaustion DoSPriority HIGH 77
    • TI-2026-64816 Netty before 4.2.18.Final QpackEncoder Unbounded Memory RetentionPriority HIGH 77
    Show all 7 records →

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat OpenShift Dev SpacesAffectedNo fix yet
Not affected: 1 product
  • Red Hat OpenShift AI (RHOAI)

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-100661
  2. 2026-10-03 Alias added: GHSA-7m86-g9j9-26xf

References

Advisory 1

  • TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
  • TI-2026-30861 Netty: HTTP/1.0 TE+CL Coexistence Bypasses Smuggling Sanitization CVSS 3.1CRITICAL 9.8
  • TI-2026-30864 Netty: HttpClientCodec response desynchronization CVSS 3.1CRITICAL 9.1
  • TI-2026-30859 Netty: DNS Codec Input Validation Bypass in Netty (Encoder + Decoder) CVSS 3.1CRITICAL 9.1
  • TI-2026-64821 Netty 4.2.11 through 4.2.17 QUIC Hostname Verification Bypass CVSS 4.0HIGH 8.7
  • TI-2026-64818 Netty HTTP/3 QPACK encoder-stream unbounded memory exhaustion DoS CVSS 4.0HIGH 8.7
See all 114 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences