CVE-2026-33870

*_This is a vulnerability in a non-Atlassian Jira dependency. Atlassian's application of this dependency presents a lower, non-critical assessed risk._* This High severity HTTP Request Smuggling vulnerability was introduced in versions 9.12.1, 10.3.0, 11.3.0 of Jira Software Data Center and Jira Software Server. This HTTP Request Smuggling vulnerability, with a CVSS Score of 7.5 and a CVSS Vector of CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N allows an unauthenticated attacker to potentially smuggle HTTP requests via crafted chunked transfer encoding extension values, which has no impact to confidentiality, high impact to integrity, no impact to availability, and requires no user interaction. Atlassian recommends that Jira Software Data Center and Jira Software Server customers upgrade to the latest version. If you are unable to do so, upgrade your instance to one of the specified supported fixed versions: * Jira Software Data Center and Server 11.3: Upgrade to a release greater than or equal to 11.3.5 * Jira Software Data Center and Server 10.3: Upgrade to a release greater than or equal to 10.3.22 * Jira Software Data Center and Server 9.12: Upgrade to a release greater than or equal to 9.12.28 See the release notes ([https://www.atlassian.com/software/jira/download-archives]). You can download the latest version of Jira Software Data Center from the download center ([https://confluence.atlassian.com/jirasoftware/jira-software-release-notes-776821069.html]). The National Vulnerability Database provides the following description for this vulnerability: Netty is an asynchronous, event-driven network application framework. In versions prior to 4.1.132.Final and 4.2.10.Final, Netty incorrectly parses quoted strings in HTTP/1.1 chunked transfer encoding extension values, enabling request smuggling attacks. Versions 4.1.132.Final and 4.2.10.Final fix the issue.

EPSS 0.64% · 47.3th percentile