7.5

CVE-2026-84375: js-yaml: maxTotalMergeKeys does not limit CPU use for empty merge sources

Deferred
AliasesRHSA-2026:62810RHSA-2026:62813UBUNTU-CVE-2026-84375
Published 01-09-2026Last modified 28-09-2026

Vulnerability summary

CVE-2026-84375 is a high (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in nodeca js-yaml. EPSS estimates a 0.54% chance of exploitation in the next 30 days, higher than 45.5% of scored vulnerabilities.

Priority
Prioritisesevere

Severe, CVSS 7.5 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 1% (FIRST, 03-11-2026)

Source freshness unavailable

How is this decided?
CVSS score
7.5/10
010
High · v3.1 (CVE.org)
EPSS score
0.54%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 3
RHSA-2026:63164RHSA-2026:63165RHSA-2026:71113

Timeline

  1. 01-09-2026
    PublishedVulnerability first disclosed.
  2. 28-09-2026
    Last modifiedVulnerability information updated.

Description

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.

CVSS metrics

8 scores · 8 sources · 1 version

EPSS trend

Probability

0.54%

Chance of exploitation in the next 30 days

Percentile

46%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.54% 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

0 found

No public exploits indexed.

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.

Chainguard81 products
  • airflow-2All versions (No fix recorded)
  • airflow-core-2All versions (No fix recorded)
  • arangodb-3.12< 3.12.9.4-r35
  • argo-workflows-ui-4.0< 4.0.11-r0
  • authentik-2025.12All versions (No fix recorded)
Wolfi14 products
  • argo-workflows-ui-4.0< 4.0.11-r0
  • code-server< 4.136.2-r1
  • eslint< 10.10.0-r1
  • jupyter-base-notebook< 7.6.3-r2
  • katib-suggestion-hyperopt< 0.19.0-r40
Redhat2 products
  • grafana12.4< 0:12.4.9-0.5.hum1
  • grafana13.2< 0:13.2.0-0.1.4.hum1
Debian1 product
  • node-js-yamlAll versions (No fix recorded) | < 4.3.2+~4.0.9-1
Nodeca1 product
  • js-yaml≥ 3.0.0, < 3.15.2 | ≥ 4.0.0, < 4.3.2 | ≥ 5.0.0, < 5.4.1
Npm1 product
  • js-yaml≥ 4.0.0, < 4.3.2 | ≥ 3.0.0, < 3.15.2
Ubuntu1 product
  • node-js-yamlAll versions (No fix recorded)

7 vendors · 101 products

References

22 links
Show all 22 references