CVE-2026-27601

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.

CVSS Metrics

• v4.0•HIGH•Score: 8.2CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
• v4.0•HIGH•Score: 8.2CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
• v3.1•MEDIUM•Score: 5.9CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Trends

Current EPSS score: 0.96%• Percentile: 60%

Techniques & Countermeasures

• CWE-770•Allocation of Resources Without Limits or Throttling

  The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

Affected Systems

• chainguard•arangodb-3.11

  all | < 3.11.14.5-r20

• chainguard•arangodb-3.12

  < 3.12.9.4-r29

• chainguard•drupal-11.3

  < 11.3.13-r3

• chainguard•jupyter-base-notebook

  all

• chainguard•katib-earlystopping

  < 0.19.0-r31

• chainguard•katib-suggestion-goptuna-compat

  < 0.19.0-r40

• chainguard•katib-suggestion-hyperband

  < 0.19.0-r31

• chainguard•katib-suggestion-hyperopt

  < 0.19.0-r31 | < 0.19.0-r40

• chainguard•katib-suggestion-nas-darts

  < 0.19.0-r31

• chainguard•katib-suggestion-nas-enas

  < 0.19.0-r31

• chainguard•katib-suggestion-optuna-enas

  < 0.19.0-r31

• chainguard•katib-suggestion-pbt-enas

  < 0.19.0-r31

• chainguard•katib-suggestion-skopt-enas

  < 0.19.0-r31

• chainguard•katib-tfevent-metricscollector

  < 0.19.0-r31

• chainguard•kubeflow-centraldashboard

  < 1.10.0-r13

• chainguard•nextcloud-server-31

  all

• chainguard•prism

  < 5.14.3-r9

• chainguard•renovate

  < 43.55.3-r0 | < 43.55.6-r0

• chainguard•vitess-21

  all

• chainguard•vitess-22

  < 22.0.4-r5

• chainguard•vitess-23

  < 23.0.3-r6

• wolfi•jupyter-base-notebook

  all

• wolfi•katib-earlystopping

  < 0.19.0-r31

• wolfi•katib-suggestion-goptuna-compat

  < 0.19.0-r40

• wolfi•katib-suggestion-hyperband

  < 0.19.0-r31

• wolfi•katib-suggestion-hyperopt

  < 0.19.0-r31 | < 0.19.0-r40

• wolfi•katib-suggestion-nas-darts

  < 0.19.0-r31

• wolfi•katib-suggestion-nas-enas

  < 0.19.0-r31

• wolfi•katib-suggestion-optuna-enas

  < 0.19.0-r31

• wolfi•katib-suggestion-pbt-enas

  < 0.19.0-r31

• wolfi•katib-suggestion-skopt-enas

  < 0.19.0-r31

• wolfi•katib-tfevent-metricscollector

  < 0.19.0-r31

• wolfi•kubeflow-centraldashboard

  < 1.10.0-r13

• wolfi•prism

  < 5.14.3-r9

• wolfi•renovate

  < 43.55.3-r0 | < 43.55.6-r0

• wolfi•vitess-23

  < 23.0.3-r6

• debian•underscore

  all | all | all | < 1.13.8~dfsg+~1.13.0-1

• ubuntu•ruby-rails-assets-underscore

  all | all | all | all

• jashkenas•underscore

  < 1.13.8

• Npm•underscore

  < 1.13.8

• underscorejs•underscore

  < 1.13.8

References (13)

• https://github.com/jashkenas/underscore/security/advisories/GHSA-qpx9-hpmf-5gmw
• https://github.com/jashkenas/underscore/commit/411e222eb0ca5d570cc4f6315c02c05b830ed2b4
• https://github.com/jashkenas/underscore/commit/a6e23ae9647461ec33ad9f92a2ecfc220eea0a84
• https://nvd.nist.gov/vuln/detail/CVE-2026-27601
• https://github.com/jashkenas/underscore/issues/3011
• https://github.com/jashkenas/underscore
• https://underscorejs.org/#1.13.8
• https://underscorejs.org/#flatten
• https://underscorejs.org/#isEqual
• https://ubuntu.com/security/CVE-2026-27601
• https://www.cve.org/CVERecord?id=CVE-2026-27601
• https://security-tracker.debian.org/tracker/CVE-2026-27601
• https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27601.json