CVE-2026-73643 (GCVE-0-2026-73643)

Vulnerability from cvelistv5 – Published: 2026-08-13 17:47 – Updated: 2026-08-14 16:44
VLAI
Title
js-yaml: Exponential parsing time in the flow collections leads to denial of service
Summary
js-yaml is a JavaScript YAML parser and dumper. From 5.0.0 until 5.2.2, parsing a small YAML document can take exponential time when an application calls load() or loadAll() on untrusted input. In src/parser/parser.ts, readFlowCollection uses restoreState and calls parseNode a second time when a flow-sequence entry is recognized as a key: value pair. If the key is a nested flow sequence of the same shape, every level is parsed twice, causing O(2^n) work and allowing an input under 200 bytes to keep one CPU busy for minutes, block the Node.js event loop, and stall the process. No anchors, aliases, merges, tags, or nondefault options are required. This issue is fixed in version 5.2.2.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: poc Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-14 16:43 UTC
CWE
  • CWE-407 - Inefficient Algorithmic Complexity
Assigner
References
Impacted products
Vendor Product Version CPE status
nodeca js-yaml Affected: >= 5.0.0, < 5.2.2
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-73643",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-14T16:43:36.799144Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-08-14T16:44:08.839Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/nodeca/js-yaml/security/advisories/GHSA-pm4m-ph32-ghv5"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "js-yaml",
          "vendor": "nodeca",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 5.0.0, \u003c 5.2.2"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "js-yaml is a JavaScript YAML parser and dumper. From 5.0.0 until 5.2.2, parsing a small YAML document can take exponential time when an application calls load() or loadAll() on untrusted input. In src/parser/parser.ts, readFlowCollection uses restoreState and calls parseNode a second time when a flow-sequence entry is recognized as a key: value pair. If the key is a nested flow sequence of the same shape, every level is parsed twice, causing O(2^n) work and allowing an input under 200 bytes to keep one CPU busy for minutes, block the Node.js event loop, and stall the process. No anchors, aliases, merges, tags, or nondefault options are required. This issue is fixed in version 5.2.2."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-407",
              "description": "CWE-407: Inefficient Algorithmic Complexity",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-13T17:47:30.404Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/nodeca/js-yaml/security/advisories/GHSA-pm4m-ph32-ghv5",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/nodeca/js-yaml/security/advisories/GHSA-pm4m-ph32-ghv5"
        },
        {
          "name": "https://github.com/nodeca/js-yaml/commit/3e5240f9cbe645ce5afb58524954a13c8539c853",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/nodeca/js-yaml/commit/3e5240f9cbe645ce5afb58524954a13c8539c853"
        }
      ],
      "source": {
        "advisory": "GHSA-pm4m-ph32-ghv5",
        "discovery": "UNKNOWN"
      },
      "title": "js-yaml: Exponential parsing time in the flow collections leads to denial of service"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-73643",
    "datePublished": "2026-08-13T17:47:30.404Z",
    "dateReserved": "2026-08-13T14:04:09.603Z",
    "dateUpdated": "2026-08-14T16:44:08.839Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-73643",
      "date": "2026-09-01",
      "epss": "0.00344",
      "percentile": "0.27149"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-73643\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-08-13T18:18:19.947\",\"lastModified\":\"2026-08-14T17:20:35.520\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"js-yaml is a JavaScript YAML parser and dumper. From 5.0.0 until 5.2.2, parsing a small YAML document can take exponential time when an application calls load() or loadAll() on untrusted input. In src/parser/parser.ts, readFlowCollection uses restoreState and calls parseNode a second time when a flow-sequence entry is recognized as a key: value pair. If the key is a nested flow sequence of the same shape, every level is parsed twice, causing O(2^n) work and allowing an input under 200 bytes to keep one CPU busy for minutes, block the Node.js event loop, and stall the process. No anchors, aliases, merges, tags, or nondefault options are required. This issue is fixed in version 5.2.2.\"}],\"affected\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"nodeca\",\"product\":\"js-yaml\",\"versions\":[{\"version\":\"\u003e= 5.0.0, \u003c 5.2.2\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":7.5,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":3.6}],\"ssvcV203\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"ssvcData\":{\"timestamp\":\"2026-08-14T16:43:36.799144Z\",\"id\":\"CVE-2026-73643\",\"options\":[{\"exploitation\":\"poc\"},{\"automatable\":\"yes\"},{\"technicalImpact\":\"partial\"}],\"role\":\"CISA Coordinator\",\"version\":\"2.0.3\"}}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-407\"}]}],\"references\":[{\"url\":\"https://github.com/nodeca/js-yaml/commit/3e5240f9cbe645ce5afb58524954a13c8539c853\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/nodeca/js-yaml/security/advisories/GHSA-pm4m-ph32-ghv5\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/nodeca/js-yaml/security/advisories/GHSA-pm4m-ph32-ghv5\",\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-09-01T12:30:19+00:00",
      "cve": "CVE-2026-73643",
      "id": "CVE-2026-73643",
      "initial_release_date": "2026-08-13T17:47:30.404000+00:00",
      "product_status:fixed": "18",
      "product_status:known_affected": "54",
      "product_status:known_not_affected": "946",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "js-yaml: js-yaml: Denial of Service via exponential parsing in flow collections",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-73643.json",
      "version": "3"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.