CVE catalog
CVE-2026-84375
js-yaml is a JavaScript YAML parser and dumper. From 3.0.0 until 3.15.2, 4.3.2, and 5.4.1, maxTotalMergeKeys in lib/js-yaml/loader.js and lib/loader.js does not count empty mapping sources while proce
- Severity
- High · CVSS 7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Published
- Updated
- Source
- [NVD] · [CVE record]
- EPSS
- 0.54% · Oct 25, 2026
js-yaml is a JavaScript YAML parser and dumper. From 3.0.0 until 3.15.2, 4.3.2, and 5.4.1, maxTotalMergeKeys in lib/js-yaml/loader.js and lib/loader.js does not count empty mapping sources while processing the merge key <<. An attacker can alias a large sequence of empty mappings into many merge targets, causing O(N * K) processing while totalMergeKeys remains unchanged and the configured resource limit is never reached. A relatively small YAML document can therefore cause prolonged CPU consumption in applications that parse untrusted YAML, and merge processing is enabled by default on these release lines. In v3 & v4, merge is enabled by default so the severity score is higher. This issue is fixed in versions 3.15.2, 4.3.2, and 5.4.1.
Vulnerable and fixed packages
Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.
| Distribution | Package | Release | Version | Status |
|---|---|---|---|---|
| Debian | node-js-yaml | sid | 4.3.2+~4.0.9-1 | fixed |
| Debian | node-js-yaml | forky | 4.3.2+~4.0.9-1 | fixed |
| Debian | node-js-yaml | trixie | 4.1.0+dfsg+~4.0.5-7 | vulnerable |
| Debian | node-js-yaml | bookworm | 4.1.0+dfsg+~4.0.5-7 | vulnerable |
| Npm | js-yaml | Not reported | 3.15.2 | fixed |
Fixed-version evidence
| Distribution | Package | Type | Release | Fixed version | Urgency | Origin | Bugs |
|---|---|---|---|---|---|---|---|
| Debian | node-js-yaml | source | sid | 4.3.2+~4.0.9-1 | not yet assigned | Not reported | [1146637] |
| Debian | node-js-yaml | source | forky | 4.3.2+~4.0.9-1 | not yet assigned | Not reported | [1146637] |
| Debian | node-js-yaml | source | trixie | (unfixed) | not yet assigned | Not reported | [1146637] |
| Debian | node-js-yaml | source | bookworm | (unfixed) | not yet assigned | Not reported | [1146637] |
| Npm | js-yaml | npm | Not reported | 3.15.2 | Not reported | GHSA-2883-XCG3-V3HH | Not reported |
Notes
[trixie] node-js-yaml: Minor issue [bookworm] node-js-yaml: Minor issue
OpenFactory catalog packages
[Debian 12 (Bookworm)]
- [node-js-yaml]Affected
Details (2)
4.1.0+dfsg+~4.0.5-7· all · bookwormAffected
nvd · node-js-yaml · debian · bookworm; nvd · node-js-yaml · debian · 12
4.1.0+dfsg+~4.0.5-7· all · bookwormAffected
nvd · node-js-yaml · debian · bookworm; nvd · node-js-yaml · debian · 12
[Debian 13 (Trixie)]
- [node-js-yaml]Affected
Details (2)
4.1.0+dfsg+~4.0.5-7· all · trixieAffected
nvd · node-js-yaml · debian · 13
4.1.0+dfsg+~4.0.5-7· all · trixieAffected
nvd · node-js-yaml · debian · 13
Observed:
References
- [https://ftp.suse.com/pub/projects/security/]
- [https://github.com/advisories/GHSA-2883-xcg3-v3hh]
- [https://nvd.nist.gov/vuln/detail/CVE-2026-84375]
- [https://osv.dev/vulnerability/DEBIAN-CVE-2026-84375]
- [https://security-tracker.debian.org/tracker/CVE-2026-84375]
- [https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-84375.json]
- [https://wid.cert-bund.de/.well-known/csaf/white/2026/wid-sec-w-2026-3596.json]
[CERT-Bund public advisories] · [Debian Security Tracker] · [FIRST EPSS] · [GitHub Advisory Database] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]