Staging Environment: Content and features may be unstable or change without notice.
Advisory details: github_osv / GHSA-4mp9-239f-g9hg
Advisory ID github_osv/GHSA-4mp9-239f-g9hg
Aliases CVE-2026-59898
Summary Netty: WebSockets V07/V08 handshaker missing Connection/Upgrade validation ## Summary An attacker can force WebSocket upgrade via the lax V07 (or V08) handshaker by sending `Sec-WebSocket-Version: 7` and omitting `Connection: Upgrade` / `Upgrade: websocket` headers, completing a protocol switch that a proxy would not recognize as an Upgrade request and enabling HTTP request smuggling / protocol-confusion attacks.
Status Published
Exploitability 0.5
Weighted Severity 5.7
Risk 2.9
Affected and Fixed Packages Package Details
Introduced and Fixed Package Commit Patches Package Commit Patches Details
Weaknesses (1)
CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
System Score Found at
cvssv4 6.3 https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-4mp9-239f-g9hg/GHSA-4mp9-239f-g9hg.json
generic_textual MODERATE
Reference id Reference type URL
https://github.com/netty/netty
https://github.com/netty/netty/releases/tag/netty-4.1.136.Final
https://github.com/netty/netty/releases/tag/netty-4.2.16.Final
https://github.com/netty/netty/security/advisories/GHSA-4mp9-239f-g9hg
No exploits are available.

No EPSS data available for this advisory.

Patch URL
There are no known patches.
Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N Found at https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-4mp9-239f-g9hg/GHSA-4mp9-239f-g9hg.json
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

low

high

none

passive

active

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none

There are no SSVC decisions available.