CVE-2026-84375: Red Hat Denial of Service vulnerability in YAML parsing
This Red Hat advisory covers CVE-2026-84375 in Red Hat Ansible Automation Platform 2.6 for RHEL 9, Network Observability (NETOBSERV) 1.12.3 and Red Hat Advanced Cluster Security for Kubernetes 4.10.
Key facts
- Vendor rating
- High, CVSS 7.5
- CISA KEV
- Not listed (catalogue checked )
- Fixed in
- 3.15.2, 4.3.2, automation-platform-ui-0:2.6.14-1.el9ap and 47 more below
- Source published
- Listed by VulniPulse
Compiled by VulniPulse from the linked sources. How records are collected and checked.
Affected products & platforms
Description
js-yaml is a JavaScript YAML parser and dumper. From 3.0.0 until 3.15.2 and 4.3.2, 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. This issue is fixed in versions 3.15.2 and 4.3.2.
An attacker can exploit this by providing a specially crafted YAML document that causes the parser to perform excessive processing when handling merge keys with empty sources. This can lead to prolonged CPU consumption, effectively causing a denial of service (DoS) for applications that process untrusted YAML input.
The flaw allows an attacker to craft a small YAML document that, when parsed, can lead to prolonged CPU consumption due to inefficient merge key processing, potentially exhausting system resources. Red Hat severity: Moderate — CVSS 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
Weakness: CWE-835.
Text from the source record.
How to fix CVE-2026-84375
Upgrade to a fixed release named by Red Hat:
- 3.15.2
- 4.3.2
- automation-platform-ui-0:2.6.14-1.el9ap
- network-observability/network-observability-console-plugin-pf5-rhel9:1789978780
- network-observability/network-observability-console-plugin-rhel9:1789978277
- advanced-cluster-security/rhacs-main-rhel8:1789411269
- advanced-cluster-security/rhacs-main-rhel9:1789411320
- ansible-automation-platform/automation-portal:1790254963
- ansible-automation-platform/automation-portal:1790256405
- ansible-automation-platform-25/lightspeed-rhel8:1789685837
- ansible-automation-platform-26/lightspeed-rhel9:1789656884
- ansible-automation-platform-tech-preview/mcp-server-rhel9:1789669036
- ansible-automation-platform-27/mcp-server-rhel9:1788915736
- container-native-virtualization/kubevirt-console-plugin:1789624656
- container-native-virtualization/kubevirt-console-plugin-rhel9:1789701168
- container-native-virtualization/kubevirt-console-plugin-rhel9:1789703476
- rhdh/red-hat-developer-hub-backstage-plugin-lightspeed:1791242743
- rhdh/red-hat-developer-hub-backstage-plugin-lightspeed-backend:1791242697
- rhdh/red-hat-developer-hub-backstage-plugin-orchestrator:1791250003
- rhdh/red-hat-developer-hub-backstage-plugin-orchestrator-backend:1791251282
- rhdh/red-hat-developer-hub-backstage-plugin-orchestrator-backend-module-loki:1791250355
- rhdh/red-hat-developer-hub-backstage-plugin-orchestrator-form-widgets:1791250794
- rhdh/red-hat-developer-hub-backstage-plugin-scaffolder-backend-module-orchestrator:1791249640
- discovery/discovery-ui-rhel9:1789677459
- rhem/flightctl-ui-ocp-rhel10:1789486226
and 25 more in the Red Hat advisory.
Support dates for the fixed release lines
- Red Hat Enterprise Linux 4: support ended
CVE-2026-84375 in other vendors' advisories
- Atlassian: CVE-2026-84375, high severity, fixed in Jira Data Center and Server: 11.3.12 (LTS) recommended Data Center Only, Jira Data Center and Server: 10.3.26 (LTS) Data Center Only, Jira Service Management Data Center and Server: 11.3.12 (LTS) recommended Data Center Only and 1 more
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