CVE-2026-41305 (GCVE-0-2026-41305)

Vulnerability from cvelistv5 – Published: 2026-04-24 02:27 – Updated: 2026-04-24 16:23
VLAI
Title
PostCSS has XSS via Unescaped </style> in its CSS Stringify Output
Summary
PostCSS takes a CSS file and provides an API to analyze and modify its rules by transforming the rules into an Abstract Syntax Tree. Versions prior to 8.5.10 do not escape `</style>` sequences when stringifying CSS ASTs. When user-submitted CSS is parsed and re-stringified for embedding in HTML `<style>` tags, `</style>` in CSS values breaks out of the style context, enabling XSS. Version 8.5.10 fixes the issue.
Severity
6.1 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
SSVC
Exploitation: poc Automatable: no Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
  • CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Assigner
References
Impacted products
Vendor Product Version
postcss postcss Affected: < 8.5.10
Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-41305",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-24T16:22:58.569354Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-04-24T16:23:41.198Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/postcss/postcss/security/advisories/GHSA-qx2v-qp2m-jg93"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "postcss",
          "vendor": "postcss",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 8.5.10"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "PostCSS takes a CSS file and provides an API to analyze and modify its rules by transforming the rules into an Abstract Syntax Tree. Versions prior to 8.5.10 do not escape `\u003c/style\u003e` sequences when stringifying CSS ASTs. When user-submitted CSS is parsed and re-stringified for embedding in HTML `\u003cstyle\u003e` tags, `\u003c/style\u003e` in CSS values breaks out of the style context, enabling XSS. Version 8.5.10 fixes the issue."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 6.1,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "integrityImpact": "LOW",
            "privilegesRequired": "NONE",
            "scope": "CHANGED",
            "userInteraction": "REQUIRED",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-79",
              "description": "CWE-79: Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-24T02:27:47.719Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/postcss/postcss/security/advisories/GHSA-qx2v-qp2m-jg93",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/postcss/postcss/security/advisories/GHSA-qx2v-qp2m-jg93"
        },
        {
          "name": "https://github.com/postcss/postcss/releases/tag/8.5.10",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/postcss/postcss/releases/tag/8.5.10"
        }
      ],
      "source": {
        "advisory": "GHSA-qx2v-qp2m-jg93",
        "discovery": "UNKNOWN"
      },
      "title": "PostCSS has XSS via Unescaped \u003c/style\u003e in its CSS Stringify Output"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-41305",
    "datePublished": "2026-04-24T02:27:47.719Z",
    "dateReserved": "2026-04-20T14:01:46.670Z",
    "dateUpdated": "2026-04-24T16:23:41.198Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-41305",
      "date": "2026-07-26",
      "epss": "0.00205",
      "percentile": "0.10699"
    },
    "microsoft_vex": {
      "current_release_date": "2026-04-30T01:52:52.000Z",
      "cve": "CVE-2026-41305",
      "id": "msrc_CVE-2026-41305",
      "initial_release_date": "2026-04-02T00:00:00.000Z",
      "product_status:known_not_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "PostCSS has XSS via Unescaped \u003c/style\u003e in its CSS Stringify Output",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-41305.json",
      "version": "3"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-41305\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-04-24T03:16:11.547\",\"lastModified\":\"2026-06-17T10:46:28.700\",\"vulnStatus\":\"Deferred\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"PostCSS takes a CSS file and provides an API to analyze and modify its rules by transforming the rules into an Abstract Syntax Tree. Versions prior to 8.5.10 do not escape `\u003c/style\u003e` sequences when stringifying CSS ASTs. When user-submitted CSS is parsed and re-stringified for embedding in HTML `\u003cstyle\u003e` tags, `\u003c/style\u003e` in CSS values breaks out of the style context, enabling XSS. Version 8.5.10 fixes the issue.\"}],\"affected\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"postcss\",\"product\":\"postcss\",\"versions\":[{\"version\":\"\u003c 8.5.10\",\"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:R/S:C/C:L/I:L/A:N\",\"baseScore\":6.1,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"REQUIRED\",\"scope\":\"CHANGED\",\"confidentialityImpact\":\"LOW\",\"integrityImpact\":\"LOW\",\"availabilityImpact\":\"NONE\"},\"exploitabilityScore\":2.8,\"impactScore\":2.7}],\"ssvcV203\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"ssvcData\":{\"timestamp\":\"2026-04-24T16:22:58.569354Z\",\"id\":\"CVE-2026-41305\",\"options\":[{\"exploitation\":\"poc\"},{\"automatable\":\"no\"},{\"technicalImpact\":\"partial\"}],\"role\":\"CISA Coordinator\",\"version\":\"2.0.3\"}}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-79\"}]}],\"references\":[{\"url\":\"https://github.com/postcss/postcss/releases/tag/8.5.10\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/postcss/postcss/security/advisories/GHSA-qx2v-qp2m-jg93\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/postcss/postcss/security/advisories/GHSA-qx2v-qp2m-jg93\",\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-07-02T17:16:41+00:00",
      "cve": "CVE-2026-41305",
      "id": "CVE-2026-41305",
      "initial_release_date": "2026-04-24T02:27:47.719000+00:00",
      "product_status:known_affected": "128",
      "product_status:known_not_affected": "2",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "postcss: PostCSS: Cross-Site Scripting (XSS) via improper escaping of style closing tags",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-41305.json",
      "version": "3"
    },
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-41305\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"poc\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-04-24T16:22:58.569354Z\"}}}], \"references\": [{\"url\": \"https://github.com/postcss/postcss/security/advisories/GHSA-qx2v-qp2m-jg93\", \"tags\": [\"exploit\"]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-04-24T16:23:25.257Z\"}}], \"cna\": {\"title\": \"PostCSS has XSS via Unescaped \u003c/style\u003e in its CSS Stringify Output\", \"source\": {\"advisory\": \"GHSA-qx2v-qp2m-jg93\", \"discovery\": \"UNKNOWN\"}, \"metrics\": [{\"cvssV3_1\": {\"scope\": \"CHANGED\", \"version\": \"3.1\", \"baseScore\": 6.1, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"MEDIUM\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N\", \"integrityImpact\": \"LOW\", \"userInteraction\": \"REQUIRED\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"NONE\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"LOW\"}}], \"affected\": [{\"vendor\": \"postcss\", \"product\": \"postcss\", \"versions\": [{\"status\": \"affected\", \"version\": \"\u003c 8.5.10\"}]}], \"references\": [{\"url\": \"https://github.com/postcss/postcss/security/advisories/GHSA-qx2v-qp2m-jg93\", \"name\": \"https://github.com/postcss/postcss/security/advisories/GHSA-qx2v-qp2m-jg93\", \"tags\": [\"x_refsource_CONFIRM\"]}, {\"url\": \"https://github.com/postcss/postcss/releases/tag/8.5.10\", \"name\": \"https://github.com/postcss/postcss/releases/tag/8.5.10\", \"tags\": [\"x_refsource_MISC\"]}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"PostCSS takes a CSS file and provides an API to analyze and modify its rules by transforming the rules into an Abstract Syntax Tree. Versions prior to 8.5.10 do not escape `\u003c/style\u003e` sequences when stringifying CSS ASTs. When user-submitted CSS is parsed and re-stringified for embedding in HTML `\u003cstyle\u003e` tags, `\u003c/style\u003e` in CSS values breaks out of the style context, enabling XSS. Version 8.5.10 fixes the issue.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-79\", \"description\": \"CWE-79: Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)\"}]}], \"providerMetadata\": {\"orgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"shortName\": \"GitHub_M\", \"dateUpdated\": \"2026-04-24T02:27:47.719Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-41305\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-04-24T16:23:41.198Z\", \"dateReserved\": \"2026-04-20T14:01:46.670Z\", \"assignerOrgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"datePublished\": \"2026-04-24T02:27:47.719Z\", \"assignerShortName\": \"GitHub_M\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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.