5.3

CVE-2026-53550: js-yaml: Quadratic-complexity DoS in merge key handling via repeated aliases

Analyzed
AliasesUBUNTU-CVE-2026-53550DEBIAN-CVE-2026-53550CGA-2837-hggw-v4c9
Published 22-06-2026Last modified 29-06-2026

Vulnerability summary

CVE-2026-53550 is a medium (CVSS 5.3) Inefficient Algorithmic Complexity vulnerability in nodeca js-yaml. EPSS estimates a 0.41% chance of exploitation in the next 30 days, higher than 35.9% of scored vulnerabilities. 1 public exploit is recorded.

Priority
Routine

Not severe (CVSS 5.3, network access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
5.3/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.41%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits1github

Advisory lineage

Upstream 0 · Downstream 9 · Related 7
OPENSUSE-SU-2026:11149-1OPENSUSE-SU-2026:11452-1OPENSUSE-SU-2026:11680-1OPENSUSE-SU-2026:12070-1OPENSUSE-SU-2026:21176-1OPENSUSE-SU-2026:21448-1

Timeline

  1. 22-06-2026
    PublishedVulnerability first disclosed.
  2. 29-06-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

7 scores · 7 sources · 1 version

EPSS trend

Probability

0.41%

Chance of exploitation in the next 30 days

Percentile

36%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.41% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

1 found
  • githubUnverified

    Js Yaml

    Maturity: poc

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Chainguard139 products
  • airflow-2All versions (No fix recorded)
  • airflow-3< 3.2.2-r8
  • airflow-core-2All versions (No fix recorded)
  • arangodb-3.11< 3.11.14.4-r5 | < 3.11.14.4-r7
  • arangodb-3.12< 3.12.9.4-r3
Wolfi40 products
  • airflow-3< 3.2.2-r8
  • argo-workflows-ui-3.7< 3.7.15-r2
  • argo-workflows-ui-4.0< 4.0.6-r2 | < 4.0.11-r0
  • code-server< 4.124.2-r0
  • eslint< 10.5.0-r1
Debian1 product
  • node-js-yamlAll versions (No fix recorded) | < 4.2.0+~4.0.9-1
Nodeca1 product
  • js-yaml< 3.15.0 | ≥ 4.0.0, < 4.2.0
Npm1 product
  • js-yaml≥ 4.0.0, < 4.2.0 | < 3.15.0
Opensuse1 product
  • python-pydata-sphinx-theme&distro=openSUSE Tumbleweed< 0.19.0-1.1
Ubuntu1 product
  • node-js-yamlAll versions (No fix recorded)

7 vendors · 184 products

References

8 links