Description
js-yaml is a JavaScript YAML parser and dumper. Prior to 4.2.0 and 3.15.0, a crafted YAML document can trigger algorithmic CPU exhaustion in js-yaml merge-key processing (<<) by repeating the same alias many times in a merge sequence. This causes quadratic parse-time behavior relative to input size and can block a Node.js worker/event loop for seconds with a relatively small payload (tens of KB), resulting in denial of service. The issue is in merge handling inside lib/loader.js. This vulnerability is fixed in 4.2.0 and 3.15.0.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| nodeca | js-yaml | >= 4.0.0, < 4.2.0, < 3.15.0 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | node-js-yaml | 4.2.0+~4.0.9-1 | — |
| Debian 13 | node-js-yaml | No fix yet | — |
| Debian 12 | node-js-yaml | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | node-js-yaml | No fix yet | — |
| Ubuntu 26.04 LTS | node-js-yaml | No fix yet | — |
| Ubuntu 25.10 | node-js-yaml | No fix yet | — |
| Ubuntu 24.04 LTS | node-js-yaml | No fix yet | — |
| Ubuntu 22.04 LTS | node-js-yaml | No fix yet | — |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | node-js-yaml | No fix yet | — |
| Ubuntu 18.04 LTS | node-js-yaml | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat Hardened Images 1 | nodejs24 +6 | 24.18.0-0.3.hum1 | RHSA-2026:38236 |
| Red Hat Hardened Images 1 | nodejs24-npm | 11.16.0-1.24.18.0.0.3.hum1 | RHSA-2026:38236 |
| Red Hat Hardened Images 1 | nodejs25 +6 | 25.9.0-1.3.hum1 | RHSA-2026:37534 |
| Red Hat Hardened Images 1 | nodejs25-npm | 11.12.1-1.25.9.0.1.3.hum1 | RHSA-2026:37534 |
| Red Hat Hardened Images 1 | nodejs26 +6 | 26.4.0-1.3.hum1 | RHSA-2026:33866 |
| Red Hat Hardened Images 1 | nodejs26-npm | 11.17.0-1.26.4.0.1.3.hum1 | RHSA-2026:33866 |
| Red Hat Hardened Images 1 | v8-13.6-devel | 13.6.233.17-1.24.18.0.0.3.hum1 | RHSA-2026:38236 |
| Red Hat Hardened Images 1 | v8-14.1-devel | 14.1.146.11-1.25.9.0.1.3.hum1 | RHSA-2026:37534 |
| Red Hat Hardened Images 1 | v8-14.6-devel | 14.6.202.34-1.26.4.0.1.3.hum1 | RHSA-2026:33866 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | agama-integration-tests | 1785848065.5562c7c-4.1 | openSUSE-SU-2026:11452-1 |
| openSUSE Tumbleweed | agama-web-ui | 24+0.a836cced5-52.1 | openSUSE-SU-2026:11680-1 |
| openSUSE Tumbleweed | python-pydata-sphinx-theme | 0.19.0-1.1 | openSUSE-SU-2026:11148-1 |
| openSUSE Tumbleweed | python-pytest-html | 4.2.0-3.1 | openSUSE-SU-2026:11149-1 |
| openSUSE Tumbleweed | velociraptor | 0.76.7.0.git145.b60ef1146-1.1 | openSUSE-SU-2026:12070-1 |
| openSUSE Leap 16.0 | agama-web-ui | 17+673.b97ba64d6-160000.12.1 | openSUSE-SU-2026:21448-1 |
| openSUSE Leap 16.0 | python-pytest-html | 4.1.1-bp160.3.1 | openSUSE-SU-2026:21176-1 |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | airflow-3 | 3.2.2-r8 | — |
| Wolfi rolling | argo-workflows-ui-4.0 | 4.0.6-r2 | — |
| Wolfi rolling | code-server | 4.124.2-r0 | — |
| Wolfi rolling | eslint | 10.5.0-r1 | — |
| Wolfi rolling | jupyter-base-notebook | 7.6.3-r2 | — |
| Wolfi rolling | katib-earlystopping +8 | 0.19.0-r31 | — |
| Wolfi rolling | katib-suggestion-goptuna-compat | 0.19.0-r40 | — |
| Wolfi rolling | kubeflow-pipelines-apiserver +1 | 2.17.2-r4 | — |
| Wolfi rolling | kubeflow-pipelines-frontend | 2.16.1-r9 | — |
| Wolfi rolling | langfuse-3 +1 | 3.191.0-r0 | — |
| Wolfi rolling | langfuse-3-compat | 3.225.7-r6 | — |
| Wolfi rolling | lerna | 9.0.7-r10 | — |
| Wolfi rolling | opensearch-dashboards-3 +1 | 3.7.0-r2 | — |
| Wolfi rolling | prism | 5.15.11-r3 | — |
| Wolfi rolling | pulumi-language-nodejs | 3.248.0-r0 | — |
| Wolfi rolling | py3.10-jupyterlab +3 | 4.6.1-r1 | — |
| Wolfi rolling | renovate | 43.249.3-r0 | — |
| Wolfi rolling | saf | 1.6.0-r1 | — |
| Wolfi rolling | sqlpad | 7.5.7-r28 | — |
| Wolfi rolling | thingsboard-tb-web-ui +1 | 4.3.1.3-r1 | — |
| Wolfi rolling | tileserver-gl | 5.6.0-r7 | — |
| Wolfi rolling | ts-patch | 4.0.1-r41 | — |
| Wolfi rolling | vitess-24 | 24.0.1-r4 | — |
| Wolfi rolling | vitess-24-compat | 24.0.3-r7 | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| npm | js-yaml | >= 4.0.0, < 4.2.0 | 4.2.0 | GHSA-h67p-54hq-rp68 |
| npm | js-yaml | < 3.15.0 | 3.15.0 | GHSA-h67p-54hq-rp68 |
Advisories 11
- RHSA-2026:38236 Red Hat Security Advisory: Red Hat Hardened Images RPMs Security Update Red Hat Security Advisories (RHSA) · Oct 20, 2026
- RHSA-2026:37534 Red Hat Security Advisory: Red Hat Hardened Images RPMs Security Update Red Hat Security Advisories (RHSA) · Oct 20, 2026
- RHSA-2026:33866 Red Hat Security Advisory: Red Hat Hardened Images RPMs Security Update Red Hat Security Advisories (RHSA) · Oct 20, 2026
- openSUSE-SU-2026:12070-1 velociraptor-0.76.7.0.git145.b60ef1146-1.1 on GA media SUSE / openSUSE Security Updates · Oct 7, 2026
- WID-SEC-2026-2618 IBM App Connect Enterprise: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 4, 2026
- openSUSE-SU-2026:11680-1 agama-web-ui-24+0.a836cced5-52.1 on GA media SUSE / openSUSE Security Updates · Sep 5, 2026
- openSUSE-SU-2026:11452-1 agama-integration-tests-1785848065.5562c7c-4.1 on GA media SUSE / openSUSE Security Updates · Aug 6, 2026
- openSUSE-SU-2026:21448-1 Security update for agama-web-ui SUSE / openSUSE Security Updates · Jul 29, 2026
- openSUSE-SU-2026:21176-1 Security update for python-pytest-html SUSE / openSUSE Security Updates · Jul 2, 2026
- openSUSE-SU-2026:11149-1 python311-pytest-html-4.2.0-3.1 on GA media SUSE / openSUSE Security Updates · Jun 30, 2026
- openSUSE-SU-2026:11148-1 python311-pydata-sphinx-theme-0.19.0-1.1 on GA media SUSE / openSUSE Security Updates · Jun 30, 2026