Netty HTTP/3 QPACK Blocked Streams Memory Exhaustion
Netty is a network application framework for development of protocol servers and clients. Starting in version 4.2.0.Final and prior to version 4.2.15.Final, a memory exhaustion vulnerability in the Netty HTTP/3 codec allows the creation of an infinite number of blocked streams, which can cause OOM error. Version 4.2.15.Final patches the issue.
- Published
- Jun 12, 2026
- Updated
- Aug 4, 2026
- EPSS
- 0.7% · 51th percentile
- CWE
- CWE-770
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Report tools
Action score
30
Monitor
Low priority for now.
- CVSS
- 30 / 40 · 7.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.7%
CISA SSVC decision
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · GitHub_M
- 7.5
- NVD has not scored this yet; the score shown is the CNA’s.
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpAffected systems
| Vendor | Product | CPE |
|---|---|---|
| netty | netty | cpe:2.3:a:netty:netty |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- netty netty4.2.0 and later · before 4.2.15
Versions reported by the vendor
Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.
netty netty
- >= 4.2.0.Final, < 4.2.15.Finalaffected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | netty | all versions | — |
| Maven | io.netty:netty-codec-http3 | from 4.2.0.Final · before 4.2.15.Final | 4.2.15.Final |
Same product
netty: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-47691Netty has Insufficient Bailiwick Validation for NS Records40Plan
- CVE-2026-45674Netty Vulnerable to DNS Cache Poisoning via Missing Bailiwick Checks in CNAME Records40Plan
- CVE-2019-20445HttpObjectDecoder.java in Netty before 4.1.44 allows a Content-Length header to be accompanied by a second Content-Length header, or by a Tr40Plan
- CVE-2026-42581Netty: HTTP/1.0 TE+CL Coexistence Bypasses Smuggling Sanitization39Monitor
- CVE-2019-20444HttpObjectDecoder.java in Netty before 4.1.44 allows an HTTP header that lacks a colon, which might be interpreted as a separate header with39Monitor
- CVE-2026-75595Netty: SNI Routing Bypass via Fragmented TLS ClientHello Causing Fallback to Default SslContext36Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Maven:io.netty:netty-codec-http3 | 4.2.15.Final | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2026-3387177 days apartNetty HTTP/2 CONTINUATION Frame Flood DoS via Zero-Byte Frame Bypass34Monitor
- CVE-2026-100660106 days apartNetty before 4.2.18.Final QpackEncoder Unbounded Memory Retention34Monitor
- CVE-2025-55163303 days apartNetty MadeYouReset HTTP/2 DDoS Vulnerability32Monitor
- CVE-2026-454160 days apartNetty: SNI handler pre-allocates up to 16 MiB from nine attacker bytes30Monitor
- CVE-2026-463400 days apartNetty: SCTP reassembly nests buffers without bound30Monitor
- CVE-2026-4258230 days apartNetty: HTTP/3 QPACK literal unbounded allocation30Monitor
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
CWE-770 · Allocation of Resources Without Limits or ThrottlingCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- FloodingCAPEC-125likelihood: High · Medium
- Excessive AllocationCAPEC-130likelihood: Medium · Medium
- XML Ping of the DeathCAPEC-147likelihood: Low · Medium
- Exponential Data ExpansionCAPEC-197likelihood: High · Medium
- Serialized Data Parameter BlowupCAPEC-229likelihood: High · High
- Serialized Data with Nested PayloadsCAPEC-230likelihood: Medium · High
- Oversized Serialized Data PayloadsCAPEC-231likelihood: Medium · High
- HTTP DoSCAPEC-469Low
ATT&CK techniques
- Network Denial of Service:Direct Network FloodT1498.001
- Network Denial of Service:Reflection AmplificationT1498.002
- Endpoint Denial of ServiceT1499
- Endpoint Denial of Service: OS Exhaustion FloodT1499.001
- Endpoint Denial of Service:Service Exhaustion FloodT1499.002
- Endpoint Denial of Service:Application Exhaustion FloodT1499.003
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- github.com/netty/netty/commit/75127cab731ee35068d1f0667bffa188bc332f5d
- github.com/netty/netty/releases/tag/netty-4.2.15.Final
- github.com/netty/netty/security/advisories/GHSA-4grm-h2qv-h6w6
- access.redhat.com/security/cve/CVE-2026-48748
- bugzilla.redhat.com/show_bug.cgi?id=2488441
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-48748.json
Vendor advisories and official records. Exploit/PoC links are deliberately left out.