GHSA-jppx-w49h-x2qq CVE-2026-56745

Netty: [SpdyHttpDecoder] ByteBuf Reference Leak on RST_STREAM Leads to Native Memory Exhaustion

High Maven

Severity: 0.0 / 10; High · CVSS 4.0
Exploit chance (EPSS): 0.63%; Chance of exploitation in the next 30 days. Higher than 50.19% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-400 Uncontrolled Resource Consumption
Fix: 4.2.16.Final; Upgrade io.netty:netty-codec-http to this version or later

Description

The SpdyHttpDecoder handler in Netty's SPDY-to-HTTP codec allocates a pooled ByteBuf when processing a client-initiated SYN_STREAM frame with FLAG_FIN=0, storing the partially-constructed FullHttpRequest in an internal map (messageMap) to accumulate subsequent DATA frames. When the remote peer sends an RST_STREAM for that stream, or when the accumulated content exceeds maxContentLength, the decoder removes the entry from the map but never releases the pooled ByteBuf, permanently leaking the allocated memory.

Affected versions

Maven

Package	Vulnerable	Fixed in
io.netty:netty-codec-http	`>= 4.2.0.Final, < 4.2.16.Final`	`4.2.16.Final`
io.netty:netty-codec-http	`>= 4.1.0.Final, < 4.1.136.Final`	`4.1.136.Final`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

io.netty:netty-codec-http Maven → `4.2.16.Final`

maven

<dependency><groupId>io.netty</groupId><artifactId>netty-codec-http</artifactId><version>4.2.16.Final</version></dependency>

gradle

implementation("io.netty:netty-codec-http:4.2.16.Final")

Severity breakdown

CVSS 4.0 0.0

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Attack vector: Network
Attack complexity: Low
Attack requirements: None
Privileges required: None
User interaction: None
Confidentiality (vulnerable system): None
Integrity (vulnerable system): None
Availability (vulnerable system): High
Confidentiality (subsequent systems): None
Integrity (subsequent systems): None
Availability (subsequent systems): None

CVSS 3.1 7.5

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

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

Weakness

CWE-400: Uncontrolled Resource Consumption

The product does not properly control the allocation and maintenance of a limited resource.

How to prevent it

Architecture and Design: Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place. The login application should be protected against DoS attacks as much as possible. Limiting the database access, perhaps by caching result sets, can help minimize the resources expended. To further limit the potential for a DoS attack, consider tracking the rate of requests received from users and blocking requests that exceed a defined rate threshold.
Architecture and Design: Mitigation of resource exhaustion attacks requires that the target system either: recognizes the attack and denies that user further access for a given amount of time, or uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed. The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question. The second solution is simply difficult to effectively institute -- and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.
Architecture and Design: Ensure that protocols have specific limits of scale placed on them.
Implementation: Ensure that all failures in resource allocation place the system into a safe posture.

References

Advisories

nvd.nist.gov/vuln/detail/CVE-2026-56745

Packages

github.com/netty/netty

Timeline

Jul 21, 2026 Published
Sep 10, 2026 Last updated by the source
Nov 1, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-8c42-7qj2-3j46 Netty Vulnerable to Cache Poisoning and Information Disclosure via CORS Vary Header Overwrite	High	Also affects io.netty:netty-codec-http
GHSA-gcjf-9mgh-3p7g Netty: CRLF Injection via Multipart Filename in Netty HttpPostRequestEncoder	Medium	Also affects io.netty:netty-codec-http
GHSA-q4f6-jm68-57ww Netty: [HttpContentEncoder] Unbounded Per-Connection Queue Growth via HTTP/1.1 Pipelining Leads to Denial of Service	High	Also affects io.netty:netty-codec-http
GHSA-4mp9-239f-g9hg Netty: WebSockets V07/V08 handshaker missing Connection/Upgrade validation	High	Also affects io.netty:netty-codec-http
GHSA-6cqp-g7gg-8hr5 Netty: Security Control Bypass via CORS Short-Circuit Failure	Medium	Also affects io.netty:netty-codec-http
GHSA-mvh2-crg5-v77c Netty SPDY zlib header block continues decoded expansion after maxHeaderSize truncation	High	Also affects io.netty:netty-codec-http
GHSA-6jqx-86gh-f27w Netty SPDY SETTINGS frame count materializes unbounded settings map	High	Also affects io.netty:netty-codec-http
GHSA-hvcg-qmg6-jm4c Netty: HttpObjectDecoder skips arbitrary initial control characters when only initial CRLF characters are permitted	Medium	Also affects io.netty:netty-codec-http

Is this in your code?

MergeHarbor checks every repository's dependencies against this database, ranks what matters by exploitability and reachability, routes it to the owning team and opens the fix pull request.

Check your repos with MergeHarbor