CVE-2026-11856

Successfully using libcurl to do a transfer to a specific HTTP origin (`hostA`) with **Digest** authentication and then changing the origin to a different one (`hostB`) for a second transfer, reusing the same handle, makes libcurl wrongly pass on the `Authorization:` header field meant for `hostA`, to `hostB`.

CVSS v3 9.8 CRITICAL

9.8^/10

CVSS v3 : CRITICAL

Vector :

Exploitability : 3.9 / Impact : 5.9

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://curl.se/docs/CVE-2026-11856.html	Patch Vendor Advisory
https://curl.se/docs/CVE-2026-11856.json	Vendor Advisory
https://hackerone.com/reports/3793260	Exploit Issue Tracking Third Party Advisory
https://hackerone.com/reports/3793260	Exploit Issue Tracking Third Party Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-07-03 07:16

Updated : 2026-09-15 07:16

NVD link : CVE-2026-11856

Mitre link : CVE-2026-11856

CVE.ORG link : CVE-2026-11856

JSON object : View

Products Affected

haxx

curl

CWE

CWE-294

Authentication Bypass by Capture-replay

{"id": "CVE-2026-11856", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-11856", "role": "CISA Coordinator", "options": [{"exploitation": "poc"}, {"automatable": "yes"}, {"technicalImpact": "total"}], "version": "2.0.3", "timestamp": "2026-07-06T18:22:46.260282Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 9.8, "attackVector": "NETWORK", "baseSeverity": "CRITICAL", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 5.9, "exploitabilityScore": 3.9}]}, "affected": [{"source": "2499f714-1537-4658-8207-48ae4bb9eae9", "affectedData": [{"vendor": "curl", "product": "curl", "versions": [{"status": "affected", "version": "7.10.6", "lessThan": "8.14.2", "versionType": "semver"}, {"status": "affected", "version": "8.15.0", "lessThan": "8.16.1", "versionType": "semver"}, {"status": "affected", "version": "8.17.0", "lessThan": "8.20.1", "versionType": "semver"}], "defaultStatus": "unaffected"}, {"repo": "https://github.com/curl/curl.git", "vendor": "curl", "product": "curl", "versions": [{"status": "affected", "version": "334d78cd18a7310144383929bdcef34ffbf6159b", "lessThan": "5c6b4880357ab3e72967c1c45cae0f96ffabc535", "versionType": "git"}], "defaultStatus": "unaffected"}, {"vendor": "curl", "product": "curl", "versions": [{"status": "affected", "version": "8.20.0"}, {"status": "affected", "version": "8.19.0"}, {"status": "affected", "version": "8.18.0"}, {"status": "affected", "version": "8.17.0"}, {"status": "affected", "version": "8.16.0"}, {"status": "affected", "version": "8.15.0"}, {"status": "affected", "version": "8.14.1"}, {"status": "affected", "version": "8.14.0"}, {"status": "affected", "version": "8.13.0"}, {"status": "affected", "version": "8.12.1"}, {"status": "affected", "version": "8.12.0"}, {"status": "affected", "version": "8.11.1"}, {"status": "affected", "version": "8.11.0"}, {"status": "affected", "version": "8.10.1"}, {"status": "affected", "version": "8.10.0"}, {"status": "affected", "version": "8.9.1"}, {"status": "affected", "version": "8.9.0"}, {"status": "affected", "version": "8.8.0"}, {"status": "affected", "version": "8.7.1"}, {"status": "affected", "version": "8.7.0"}, {"status": "affected", "version": "8.6.0"}, {"status": "affected", "version": "8.5.0"}, {"status": "affected", "version": "8.4.0"}, {"status": "affected", "version": "8.3.0"}, {"status": "affected", "version": "8.2.1"}, {"status": "affected", "version": "8.2.0"}, {"status": "affected", "version": "8.1.2"}, {"status": "affected", "version": "8.1.1"}, {"status": "affected", "version": "8.1.0"}, {"status": "affected", "version": "8.0.1"}, {"status": "affected", "version": "8.0.0"}, {"status": "affected", "version": "7.88.1"}, {"status": "affected", "version": "7.88.0"}, {"status": "affected", "version": "7.87.0"}, {"status": "affected", "version": "7.86.0"}, {"status": "affected", "version": "7.85.0"}, {"status": "affected", "version": "7.84.0"}, {"status": "affected", "version": "7.83.1"}, {"status": "affected", "version": "7.83.0"}, {"status": "affected", "version": "7.82.0"}, {"status": "affected", "version": "7.81.0"}, {"status": "affected", "version": "7.80.0"}, {"status": "affected", "version": "7.79.1"}, {"status": "affected", "version": "7.79.0"}, {"status": "affected", "version": "7.78.0"}, {"status": "affected", "version": "7.77.0"}, {"status": "affected", "version": "7.76.1"}, {"status": "affected", "version": "7.76.0"}, {"status": "affected", "version": "7.75.0"}, {"status": "affected", "version": "7.74.0"}, {"status": "affected", "version": "7.73.0"}, {"status": "affected", "version": "7.72.0"}, {"status": "affected", "version": "7.71.1"}, {"status": "affected", "version": "7.71.0"}, {"status": "affected", "version": "7.70.0"}, {"status": "affected", "version": "7.69.1"}, {"status": "affected", "version": "7.69.0"}, {"status": "affected", "version": "7.68.0"}, {"status": "affected", "version": "7.67.0"}, {"status": "affected", "version": "7.66.0"}, {"status": "affected", "version": "7.65.3"}, {"status": "affected", "version": "7.65.2"}, {"status": "affected", "version": "7.65.1"}, {"status": "affected", "version": "7.65.0"}, {"status": "affected", "version": "7.64.1"}, {"status": "affected", "version": "7.64.0"}, {"status": "affected", "version": "7.63.0"}, {"status": "affected", "version": "7.62.0"}, {"status": "affected", "version": "7.61.1"}, {"status": "affected", "version": "7.61.0"}, {"status": "affected", "version": "7.60.0"}, {"status": "affected", "version": "7.59.0"}, {"status": "affected", "version": "7.58.0"}, {"status": "affected", "version": "7.57.0"}, {"status": "affected", "version": "7.56.1"}, {"status": "affected", "version": "7.56.0"}, {"status": "affected", "version": "7.55.1"}, {"status": "affected", "version": "7.55.0"}, {"status": "affected", "version": "7.54.1"}, {"status": "affected", "version": "7.54.0"}, {"status": "affected", "version": "7.53.1"}, {"status": "affected", "version": "7.53.0"}, {"status": "affected", "version": "7.52.1"}, {"status": "affected", "version": "7.52.0"}, {"status": "affected", "version": "7.51.0"}, {"status": "affected", "version": "7.50.3"}, {"status": "affected", "version": "7.50.2"}, {"status": "affected", "version": "7.50.1"}, {"status": "affected", "version": "7.50.0"}, {"status": "affected", "version": "7.49.1"}, {"status": "affected", "version": "7.49.0"}, {"status": "affected", "version": "7.48.0"}, {"status": "affected", "version": "7.47.1"}, {"status": "affected", "version": "7.47.0"}, {"status": "affected", "version": "7.46.0"}, {"status": "affected", "version": "7.45.0"}, {"status": "affected", "version": "7.44.0"}, {"status": "affected", "version": "7.43.0"}, {"status": "affected", "version": "7.42.1"}, {"status": "affected", "version": "7.42.0"}, {"status": "affected", "version": "7.41.0"}, {"status": "affected", "version": "7.40.0"}, {"status": "affected", "version": "7.39.0"}, {"status": "affected", "version": "7.38.0"}, {"status": "affected", "version": "7.37.1"}, {"status": "affected", "version": "7.37.0"}, {"status": "affected", "version": "7.36.0"}, {"status": "affected", "version": "7.35.0"}, {"status": "affected", "version": "7.34.0"}, {"status": "affected", "version": "7.33.0"}, {"status": "affected", "version": "7.32.0"}, {"status": "affected", "version": "7.31.0"}, {"status": "affected", "version": "7.30.0"}, {"status": "affected", "version": "7.29.0"}, {"status": "affected", "version": "7.28.1"}, {"status": "affected", "version": "7.28.0"}, {"status": "affected", "version": "7.27.0"}, {"status": "affected", "version": "7.26.0"}, {"status": "affected", "version": "7.25.0"}, {"status": "affected", "version": "7.24.0"}, {"status": "affected", "version": "7.23.1"}, {"status": "affected", "version": "7.23.0"}, {"status": "affected", "version": "7.22.0"}, {"status": "affected", "version": "7.21.7"}, {"status": "affected", "version": "7.21.6"}, {"status": "affected", "version": "7.21.5"}, {"status": "affected", "version": "7.21.4"}, {"status": "affected", "version": "7.21.3"}, {"status": "affected", "version": "7.21.2"}, {"status": "affected", "version": "7.21.1"}, {"status": "affected", "version": "7.21.0"}, {"status": "affected", "version": "7.20.1"}, {"status": "affected", "version": "7.20.0"}, {"status": "affected", "version": "7.19.7"}, {"status": "affected", "version": "7.19.6"}, {"status": "affected", "version": "7.19.5"}, {"status": "affected", "version": "7.19.4"}, {"status": "affected", "version": "7.19.3"}, {"status": "affected", "version": "7.19.2"}, {"status": "affected", "version": "7.19.1"}, {"status": "affected", "version": "7.19.0"}, {"status": "affected", "version": "7.18.2"}, {"status": "affected", "version": "7.18.1"}, {"status": "affected", "version": "7.18.0"}, {"status": "affected", "version": "7.17.1"}, {"status": "affected", "version": "7.17.0"}, {"status": "affected", "version": "7.16.4"}, {"status": "affected", "version": "7.16.3"}, {"status": "affected", "version": "7.16.2"}, {"status": "affected", "version": "7.16.1"}, {"status": "affected", "version": "7.16.0"}, {"status": "affected", "version": "7.15.5"}, {"status": "affected", "version": "7.15.4"}, {"status": "affected", "version": "7.15.3"}, {"status": "affected", "version": "7.15.2"}, {"status": "affected", "version": "7.15.1"}, {"status": "affected", "version": "7.15.0"}, {"status": "affected", "version": "7.14.1"}, {"status": "affected", "version": "7.14.0"}, {"status": "affected", "version": "7.13.2"}, {"status": "affected", "version": "7.13.1"}, {"status": "affected", "version": "7.13.0"}, {"status": "affected", "version": "7.12.3"}, {"status": "affected", "version": "7.12.2"}, {"status": "affected", "version": "7.12.1"}, {"status": "affected", "version": "7.12.0"}, {"status": "affected", "version": "7.11.2"}, {"status": "affected", "version": "7.11.1"}, {"status": "affected", "version": "7.11.0"}, {"status": "affected", "version": "7.10.8"}, {"status": "affected", "version": "7.10.7"}, {"status": "affected", "version": "7.10.6"}], "defaultStatus": "unaffected"}]}], "published": "2026-07-03T07:16:23.973", "references": [{"url": "https://curl.se/docs/CVE-2026-11856.html", "tags": ["Patch", "Vendor Advisory"], "source": "2499f714-1537-4658-8207-48ae4bb9eae9"}, {"url": "https://curl.se/docs/CVE-2026-11856.json", "tags": ["Vendor Advisory"], "source": "2499f714-1537-4658-8207-48ae4bb9eae9"}, {"url": "https://hackerone.com/reports/3793260", "tags": ["Exploit", "Issue Tracking", "Third Party Advisory"], "source": "2499f714-1537-4658-8207-48ae4bb9eae9"}, {"url": "https://hackerone.com/reports/3793260", "tags": ["Exploit", "Issue Tracking", "Third Party Advisory"], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}], "vulnStatus": "Modified", "weaknesses": [{"type": "Secondary", "source": "2499f714-1537-4658-8207-48ae4bb9eae9", "description": [{"lang": "en", "value": "CWE-294"}]}, {"type": "Primary", "source": "nvd@nist.gov", "description": [{"lang": "en", "value": "CWE-294"}]}], "descriptions": [{"lang": "en", "value": "Successfully using libcurl to do a transfer to a specific HTTP origin\n(`hostA`) with **Digest** authentication and then changing the origin to a\ndifferent one (`hostB`) for a second transfer, reusing the same handle, makes\nlibcurl wrongly pass on the `Authorization:` header field meant for `hostA`,\nto `hostB`."}], "lastModified": "2026-09-15T07:16:25.870", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "9E12CA71-3AD8-44FB-9A48-E1CD9551EDE8", "versionEndExcluding": "8.21.0", "versionStartIncluding": "7.10.6"}], "operator": "OR"}]}], "sourceIdentifier": "2499f714-1537-4658-8207-48ae4bb9eae9"}