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Advisory details: gitlab / maven/io.netty/netty-codec-http2/CVE-2026-42587
Advisory ID gitlab/maven/io.netty/netty-codec-http2/CVE-2026-42587
Aliases CVE-2026-42587
GHSA-f6hv-jmp6-3vwv
Summary Netty: HttpContentDecompressor maxAllocation bypass when Content-Encoding set to br/zstd/snappy leads to decompression bomb DoS `HttpContentDecompressor` accepts a `maxAllocation` parameter to limit decompression buffer size and prevent decompression bomb attacks. This limit is correctly enforced for gzip and deflate encodings via `ZlibDecoder`, but is silently ignored when the content encoding is `br` (Brotli), `zstd`, or `snappy`. An attacker can bypass the configured decompression limit by sending a compressed payload with `Content-Encoding: br` instead of `Content-Encoding: gzip`, causing unbounded memory allocation and out-of-memory denial of service. The same vulnerability exists in `DelegatingDecompressorFrameListener` for HTTP/2 connections.
Status Published
Exploitability 0.5
Weighted Severity 0.0
Risk
Affected and Fixed Packages Package Details
Introduced and Fixed Package Commit Patches Package Commit Patches Details
Weaknesses (3)
CWE-400 Uncontrolled Resource Consumption
CWE-937 OWASP Top Ten 2013 Category A9 - Using Components with Known Vulnerabilities
CWE-1035 OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
System Score Found at
cvssv3.1 https://gitlab.com/gitlab-org/advisories-community/-/blob/main/maven/io.netty/netty-codec-http2/CVE-2026-42587.yml
Reference id Reference type URL
https://github.com/netty/netty/security/advisories/GHSA-f6hv-jmp6-3vwv
CVE-2026-42587 https://nvd.nist.gov/vuln/detail/CVE-2026-42587
GHSA-f6hv-jmp6-3vwv https://github.com/advisories/GHSA-f6hv-jmp6-3vwv
No exploits are available.

No EPSS data available for this advisory.

Patch URL
There are no known patches.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://gitlab.com/gitlab-org/advisories-community/-/blob/main/maven/io.netty/netty-codec-http2/CVE-2026-42587.yml
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none

Vector: SSVCv2/E:P/A:Y/T:P/P:M/B:A/M:M/D:T/2026-05-13T18:43:31Z/

Decision: Track

Source URL: https://github.com/cisagov/vulnrichment/blob/develop/2026/42xxx/CVE-2026-42587.json

Source Advisory: vulnrichment/CVE-2026-42587

View SSVC decision tree 
[{'Exploitation': 'poc'},
 {'Automatable': 'yes'},
 {'Technical Impact': 'partial'},
 {'Mission Prevalence': 'minimal'},
 {'Public Well-being Impact': 'material'},
 {'Mission & Well-being': 'medium'}]