--- title: "CVE-2026-27601\n | Ubuntu" description: Ubuntu is an open source software operating system that runs from the desktop, to the cloud, to all your internet connected things. url: https://ubuntu.com/security/CVE-2026-27601?format=md keywords: index, follow --- # CVE-2026-27601 Publication date 3 March 2026 Last updated 7 August 2026 --- Ubuntu priority **Medium** [Why this priority?](https://ubuntu.com/security/cves/about#priority ) ## Cvss 3 Severity Score **5.9 · Medium** [Score breakdown](https://ubuntu.com/security/CVE-2026-27601?format=md#impact-score) Toggle side navigation ## Description Underscore.js is a utility-belt library for JavaScript. Prior to 1.13.8, the \_.flatten and \_.isEqual functions use recursion without a depth limit. Under very specific conditions, detailed below, an attacker could exploit this in a Denial of Service (DoS) attack by triggering a stack overflow. Untrusted input must be used to create a recursive datastructure, for example using JSON.parse, with no enforced depth limit. The datastructure thus created must be passed to \_.flatten or \_.isEqual. In the case of \_.flatten, the vulnerability can only be exploited if it is possible for a remote client to prepare a datastructure that consists of arrays at all levels AND if no finite depth limit is passed as the second argument to \_.flatten. In the case of \_.isEqual, the vulnerability can only be exploited if there exists a code path in which two distinct datastructures that were submitted by the same remote client are compared using \_.isEqual. For example, if a client submits data that are stored in a database, and the same client can later submit another datastructure that is then compared to the data that were saved in the database previously, OR if a client submits a single request, but its data are parsed twice, creating two non-identical but equivalent datastructures that are then compared. Exceptions originating from the call to \_.flatten or \_.isEqual, as a result of a stack overflow, are not being caught. This vulnerability is fixed in 1.13.8. ## Status Show unmaintained releases | Package | Ubuntu Release | Status | | --- | --- | --- | | ruby-rails-assets-underscore | 26.04 LTS resolute | Not in release | | 25.10 questing | Not in release | | 24.04 LTS noble | Needs evaluation | | 22.04 LTS jammy | Needs evaluation | | 20.04 LTS focal | Needs evaluation | | 18.04 LTS bionic | Needs evaluation | --- * [How can I get the fixes?](https://ubuntu.com/security/cves/about#security) * [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses) ## Severity score breakdown CVSS version: CVSS v4.0 [CVSS v4.0](https://ubuntu.com/security/CVE-2026-27601?format=md) [CVSS v3.0](https://ubuntu.com/security/CVE-2026-27601?format=md) **Base score** 8.2 · High * Base metrics | Parameter | Value | | --- | --- | | Attack vector | Network | | Attack complexity | Low | | Attack requirements | Present | | Privileges required | None | | User interaction | None | | Vulnerable system - Confidentiality impact | None | | Vulnerable system - Integrity impact | None | | Vulnerable system - Availability impact | High | | Subsequent system - Confidentiality impact | None | | Subsequent system - Integrity impact | None | | Subsequent system - Availability impact | None | * Scores | Parameter | Value | | --- | --- | | Base score | 8.2 · High | | Base + Threat score | - | | Base + Environmental score | - | | Base + Threat + Environmental score | - | **Vector:** CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N ## References * [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-27601) * [NVD](https://nvd.nist.gov/vuln/detail/CVE-2026-27601) * [Launchpad](https://launchpad.net/bugs/cve/CVE-2026-27601) * [Debian](https://security-tracker.debian.org/tracker/CVE-2026-27601) ### Other references * * * *