CVE-2026-42580 | Netty: HTTP Request Smuggling due to incorrect chunk size parsing

Exp

Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, Netty's chunk size parser silently overflows int, enabling request smuggling attacks. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.

Published: 2026-05-13 Last update: 2026-05-18 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-42580 is rated Exploit Available (50/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.02%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2026-42580

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2026-42580

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-22 0.05% 0.02% -0.04%
2 2026-05-19 0.04% 0.05% +0.01%
3 2026-05-14 — 0.04% —

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-42580

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 2.5 [email protected]

Weakness enumeration for CVE-2026-42580

GitHub Security Advisory for CVE-2026-42580

GHSA-m4cv-j2px-7723 · Severity: medium · Ecosystem: maven — Netty vulnerable to HTTP Request Smuggling due to incorrect chunk size parsing

OS Trackers for CVE-2026-42580

vendor priority summary link
debian not yet assigned CVE-2026-42580 not yet assigned priority: Debian including 1 source packages (netty), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 5. https://security-tracker.debian.org/tracker/CVE-2026-42580
suse high — https://www.suse.com/security/cve/CVE-2026-42580/
ubuntu medium CVE-2026-42580 medium priority: Ubuntu including 1 source packages (netty), 8 status rows across 8 suites (bionic, focal, jammy, noble, questing, resolute, trusty, upstream): needs-triage 8. https://ubuntu.com/security/CVE-2026-42580

Affected software / configurations for CVE-2026-42580

Vendor Product Version Raw CPE
netty netty < 4.1.133 cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*
netty netty >= 4.2.0, < 4.2.13 cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*

References for CVE-2026-42580

cvelogic Threat Intelligence