GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

CVE-2026-80255 (GCVE-0-2026-80255)

Vulnerability from cvelistv5 – Published: 2026-09-06 17:48 – Updated: 2026-09-08 18:45
VLAI
Title
secure cookie attribute bypass with tab
Summary
A `Set-Cookie:` header using tab (horizontal tab, ASCII code 9) instead of space (ascii code 32) immediately before the `Secure` attribute causes curl to store the cookie without its Secure flag. The cookie might then wrongfully be sent over plaintext HTTP on subsequent requests to the same host.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
SSVC
Exploitation: poc Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-08 18:45 UTC
CWE
Assigner
References
Impacted products
Vendor Product Version CPE status
curl curl Affected: 8.21.0 , ≤ 8.21.0 (semver)
Affected: 8.20.0 , ≤ 8.20.0 (semver)
Affected: 8.19.0 , ≤ 8.19.0 (semver)
Affected: 8.18.0 , ≤ 8.18.0 (semver)
Affected: 8.17.0 , ≤ 8.17.0 (semver)
Affected: 8.16.0 , ≤ 8.16.0 (semver)
Affected: 8.15.0 , ≤ 8.15.0 (semver)
Affected: 8.14.1 , ≤ 8.14.1 (semver)
Affected: 8.14.0 , ≤ 8.14.0 (semver)
Affected: 8.13.0 , ≤ 8.13.0 (semver)
guessed Create a notification for this product.
Credits
Stanislav Fort (Aisle Research) Daniel Stenberg
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "cvssV3_1": {
              "attackComplexity": "LOW",
              "attackVector": "NETWORK",
              "availabilityImpact": "NONE",
              "baseScore": 7.5,
              "baseSeverity": "HIGH",
              "confidentialityImpact": "HIGH",
              "integrityImpact": "NONE",
              "privilegesRequired": "NONE",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
              "version": "3.1"
            }
          },
          {
            "other": {
              "content": {
                "id": "CVE-2026-80255",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-09-08T18:45:09.883106Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "problemTypes": [
          {
            "descriptions": [
              {
                "cweId": "CWE-201",
                "description": "CWE-201 Insertion of Sensitive Information Into Sent Data",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-09-08T18:45:49.180Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://hackerone.com/reports/3972395"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "curl",
          "vendor": "curl",
          "versions": [
            {
              "lessThanOrEqual": "8.21.0",
              "status": "affected",
              "version": "8.21.0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "8.20.0",
              "status": "affected",
              "version": "8.20.0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "8.19.0",
              "status": "affected",
              "version": "8.19.0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "8.18.0",
              "status": "affected",
              "version": "8.18.0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "8.17.0",
              "status": "affected",
              "version": "8.17.0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "8.16.0",
              "status": "affected",
              "version": "8.16.0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "8.15.0",
              "status": "affected",
              "version": "8.15.0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "8.14.1",
              "status": "affected",
              "version": "8.14.1",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "8.14.0",
              "status": "affected",
              "version": "8.14.0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "8.13.0",
              "status": "affected",
              "version": "8.13.0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Stanislav Fort (Aisle Research)"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "Daniel Stenberg"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "A `Set-Cookie:` header using tab (horizontal tab, ASCII code 9) instead of\nspace (ascii code 32) immediately before the `Secure` attribute causes curl to\nstore the cookie without its Secure flag. The cookie might then wrongfully be\nsent over plaintext HTTP on subsequent requests to the same host."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "CWE-201 Information Exposure Through Sent Data",
              "lang": "en"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-06T17:48:54.275Z",
        "orgId": "2499f714-1537-4658-8207-48ae4bb9eae9",
        "shortName": "curl"
      },
      "references": [
        {
          "name": "json",
          "url": "https://curl.se/docs/CVE-2026-80255.json"
        },
        {
          "name": "www",
          "url": "https://curl.se/docs/CVE-2026-80255.html"
        },
        {
          "name": "issue",
          "url": "https://hackerone.com/reports/3972395"
        }
      ],
      "title": "secure cookie attribute bypass with tab"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "2499f714-1537-4658-8207-48ae4bb9eae9",
    "assignerShortName": "curl",
    "cveId": "CVE-2026-80255",
    "datePublished": "2026-09-06T17:48:54.275Z",
    "dateReserved": "2026-08-26T06:25:58.220Z",
    "dateUpdated": "2026-09-08T18:45:49.180Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-80255",
      "date": "2026-09-10",
      "epss": "0.00514",
      "percentile": "0.42098"
    },
    "microsoft_vex": {
      "current_release_date": "2026-09-09T15:06:41.000Z",
      "cve": "CVE-2026-80255",
      "id": "msrc_CVE-2026-80255",
      "initial_release_date": "2026-09-08T01:04:43.000Z",
      "product_status:known_affected": "2",
      "product_status:known_not_affected": "4",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "secure cookie attribute bypass with tab",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-80255.json",
      "version": "3"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-80255\",\"sourceIdentifier\":\"2499f714-1537-4658-8207-48ae4bb9eae9\",\"published\":\"2026-09-06T18:17:22.623\",\"lastModified\":\"2026-09-08T19:19:54.520\",\"vulnStatus\":\"Undergoing Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"A `Set-Cookie:` header using tab (horizontal tab, ASCII code 9) instead of\\nspace (ascii code 32) immediately before the `Secure` attribute causes curl to\\nstore the cookie without its Secure flag. The cookie might then wrongfully be\\nsent over plaintext HTTP on subsequent requests to the same host.\"}],\"affected\":[{\"source\":\"2499f714-1537-4658-8207-48ae4bb9eae9\",\"affectedData\":[{\"vendor\":\"curl\",\"product\":\"curl\",\"defaultStatus\":\"unaffected\",\"versions\":[{\"version\":\"8.21.0\",\"lessThanOrEqual\":\"8.21.0\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"8.20.0\",\"lessThanOrEqual\":\"8.20.0\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"8.19.0\",\"lessThanOrEqual\":\"8.19.0\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"8.18.0\",\"lessThanOrEqual\":\"8.18.0\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"8.17.0\",\"lessThanOrEqual\":\"8.17.0\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"8.16.0\",\"lessThanOrEqual\":\"8.16.0\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"8.15.0\",\"lessThanOrEqual\":\"8.15.0\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"8.14.1\",\"lessThanOrEqual\":\"8.14.1\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"8.14.0\",\"lessThanOrEqual\":\"8.14.0\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"8.13.0\",\"lessThanOrEqual\":\"8.13.0\",\"versionType\":\"semver\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N\",\"baseScore\":7.5,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"NONE\"},\"exploitabilityScore\":3.9,\"impactScore\":3.6}],\"ssvcV203\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"ssvcData\":{\"timestamp\":\"2026-09-08T18:45:09.883106Z\",\"id\":\"CVE-2026-80255\",\"options\":[{\"exploitation\":\"poc\"},{\"automatable\":\"yes\"},{\"technicalImpact\":\"partial\"}],\"role\":\"CISA Coordinator\",\"version\":\"2.0.3\"}}]},\"weaknesses\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-201\"}]}],\"references\":[{\"url\":\"https://curl.se/docs/CVE-2026-80255.html\",\"source\":\"2499f714-1537-4658-8207-48ae4bb9eae9\"},{\"url\":\"https://curl.se/docs/CVE-2026-80255.json\",\"source\":\"2499f714-1537-4658-8207-48ae4bb9eae9\"},{\"url\":\"https://hackerone.com/reports/3972395\",\"source\":\"2499f714-1537-4658-8207-48ae4bb9eae9\"},{\"url\":\"https://hackerone.com/reports/3972395\",\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\"}]}}",
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-08T00:08:55Z",
      "cve": "CVE-2026-80255",
      "id": "CVE-2026-80255",
      "initial_release_date": "2026-09-08T00:08:55Z",
      "product_status:known_affected": "148",
      "product_status:known_not_affected": "38",
      "product_status:recommended": "9",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-80255",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-80255.json",
      "version": "2"
    },
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 7.5, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"HIGH\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N\", \"integrityImpact\": \"NONE\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"NONE\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"HIGH\"}}, {\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-80255\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"poc\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-09-08T18:45:09.883106Z\"}}}], \"references\": [{\"url\": \"https://hackerone.com/reports/3972395\", \"tags\": [\"exploit\"]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-201\", \"description\": \"CWE-201 Insertion of Sensitive Information Into Sent Data\"}]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-09-08T18:45:43.369Z\"}}], \"cna\": {\"title\": \"secure cookie attribute bypass with tab\", \"credits\": [{\"lang\": \"en\", \"type\": \"finder\", \"value\": \"Stanislav Fort (Aisle Research)\"}, {\"lang\": \"en\", \"type\": \"remediation developer\", \"value\": \"Daniel Stenberg\"}], \"affected\": [{\"vendor\": \"curl\", \"product\": \"curl\", \"versions\": [{\"status\": \"affected\", \"version\": \"8.21.0\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"8.21.0\"}, {\"status\": \"affected\", \"version\": \"8.20.0\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"8.20.0\"}, {\"status\": \"affected\", \"version\": \"8.19.0\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"8.19.0\"}, {\"status\": \"affected\", \"version\": \"8.18.0\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"8.18.0\"}, {\"status\": \"affected\", \"version\": \"8.17.0\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"8.17.0\"}, {\"status\": \"affected\", \"version\": \"8.16.0\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"8.16.0\"}, {\"status\": \"affected\", \"version\": \"8.15.0\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"8.15.0\"}, {\"status\": \"affected\", \"version\": \"8.14.1\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"8.14.1\"}, {\"status\": \"affected\", \"version\": \"8.14.0\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"8.14.0\"}, {\"status\": \"affected\", \"version\": \"8.13.0\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"8.13.0\"}], \"defaultStatus\": \"unaffected\"}], \"references\": [{\"url\": \"https://curl.se/docs/CVE-2026-80255.json\", \"name\": \"json\"}, {\"url\": \"https://curl.se/docs/CVE-2026-80255.html\", \"name\": \"www\"}, {\"url\": \"https://hackerone.com/reports/3972395\", \"name\": \"issue\"}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"A `Set-Cookie:` header using tab (horizontal tab, ASCII code 9) instead of\\nspace (ascii code 32) immediately before the `Secure` attribute causes curl to\\nstore the cookie without its Secure flag. The cookie might then wrongfully be\\nsent over plaintext HTTP on subsequent requests to the same host.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"description\": \"CWE-201 Information Exposure Through Sent Data\"}]}], \"providerMetadata\": {\"orgId\": \"2499f714-1537-4658-8207-48ae4bb9eae9\", \"shortName\": \"curl\", \"dateUpdated\": \"2026-09-06T17:48:54.275Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-80255\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-09-08T18:45:49.180Z\", \"dateReserved\": \"2026-08-26T06:25:58.220Z\", \"assignerOrgId\": \"2499f714-1537-4658-8207-48ae4bb9eae9\", \"datePublished\": \"2026-09-06T17:48:54.275Z\", \"assignerShortName\": \"curl\"}",
      "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.