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CVE-2026-84375

7.5 · HIGH

js-yaml is a JavaScript YAML parser and dumper.

Published Sep 1, 2026CWE-400EPSS 0.54%

Overview

CVE-2026-84375 is a high-severity vulnerability. It was published on September 1, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/nodeca/js-yaml/commit/3485bc06ff8a0251505f44a00414d90df2466639GitHubgithub.com/nodeca/js-yaml/commit/6a8e05f9a485188ed730ac81e81ae221352ef480GitHubgithub.com/nodeca/js-yaml/commit/d90b6612a5a84385bdcb556c44578eac76dc0f6bGitHubgithub.com/nodeca/js-yaml/pull/797GitHubgithub.com/nodeca/js-yaml/releases/tag/3.15.2GitHubgithub.com/nodeca/js-yaml/releases/tag/4.3.2GitHubgithub.com/nodeca/js-yaml/releases/tag/5.4.1GitHubgithub.com/nodeca/js-yaml/security/advisories/GHSA-2883-xcg3-v3hh

How CyberStrike helps

Frequently asked questions

What is CVE-2026-84375?

CVE-2026-84375 is a high-severity vulnerability. It was published on September 1, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-84375?

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-84375?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-84375?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-84375 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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