{"id":"CVE-2026-8927","title":"When reusing a libcurl handle for sequential transfers driven by\nenvironment-variable proxy configuration, libcurl fails to clear the proxy\nauthentication state between requests","summary":"When reusing a libcurl handle for sequential transfers driven by\nenvironment-variable proxy configuration, libcurl fails to clear the proxy\nauthentication state between requests. Specifically, if the initial transfer\nauthenticates agains…","severity":"critical","cvss":9.1,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","cwe":["CWE-294","CWE-201"],"vendor":"haxx","product":"curl","affected":["curl >= 7.12.0, < 8.21.0"],"patched":["curl 8.21.0"],"published":"2026-07-03","updated":"2026-09-15","sourceUpdated":"2026-09-15T07:16:33.157","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-8927","references":[{"url":"https://curl.se/docs/CVE-2026-8927.html","label":"2499f714-1537-4658-8207-48ae4bb9eae9"},{"url":"https://curl.se/docs/CVE-2026-8927.json","label":"2499f714-1537-4658-8207-48ae4bb9eae9"},{"url":"https://hackerone.com/reports/3744543","label":"2499f714-1537-4658-8207-48ae4bb9eae9"},{"url":"https://hackerone.com/reports/3744543","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-8927.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-8927"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2496769"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-8927"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-8927"},{"url":"https://access.redhat.com/errata/RHSA-2026:55432"},{"url":"https://access.redhat.com/errata/RHSA-2026:29017"},{"url":"https://access.redhat.com/errata/RHSA-2026:34975"},{"url":"https://access.redhat.com/errata/RHSA-2026:56869"},{"url":"https://access.redhat.com/errata/RHSA-2026:69126"}],"tags":["nvd","cve.org","exploit-available","csaf","vex","red-hat"],"exploitAvailable":true,"ssvc":{"exploitation":"poc","automatable":"no","technicalImpact":"total","timestamp":"2026-07-06T17:00:13.489405Z"},"epss":0.005,"epssPercentile":0.41748,"ingestedAt":"2026-07-04T04:55:39.445Z","scores":{"nvd":9.1,"vendor":7.5},"slug":"CVE-2026-8927","body":"## Overview\n\nWhen reusing a libcurl handle for sequential transfers driven by\nenvironment-variable proxy configuration, libcurl fails to clear the proxy\nauthentication state between requests. Specifically, if the initial transfer\nauthenticates against `proxyA` using Digest auth, a subsequent transfer routed\nthrough `proxyB` erroneously leaks the `Proxy-Authorization:` header intended\nsolely for `proxyA`.\n\n## Affected\n\n- `curl >= 7.12.0, < 8.21.0`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `curl 8.21.0`\n\n## Vendor advisories\n\n- **RHSA-2026:55432** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux BaseOS (v. 10) · released 2026-08-17 · [advisory](https://access.redhat.com/errata/RHSA-2026:55432)\n- **RHSA-2026:29017** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-06-24 · [advisory](https://access.redhat.com/errata/RHSA-2026:29017)\n- **RHSA-2026:34975** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-07-02 · [advisory](https://access.redhat.com/errata/RHSA-2026:34975)\n- **RHSA-2026:56869** · Red Hat · fixed in: Red Hat JBoss Core Services 2.4.62.SP5 · released 2026-08-19 · [advisory](https://access.redhat.com/errata/RHSA-2026:56869)\n- **Red Hat VEX** · Important · affected: Confidential Compute Attestation, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, … · no fix planned: Red Hat Enterprise Linux 6, Confidential Compute Attestation, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, … · updated 2026-09-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-8927.json)\n- **RHSA-2026:69126** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux BaseOS (v. 9) · released 2026-09-21 · [advisory](https://access.redhat.com/errata/RHSA-2026:69126)","depth":"abyssal","depthScore":62,"depthScoreParts":{"impact":50.1,"likelihood":0.1,"exploitation":12,"ransomware":0},"changes":[{"seq":203503,"id":"CVE-2026-8927","ts":1789457645816,"field":"exploit_available","old":"false","new":"true"},{"seq":203502,"id":"CVE-2026-8927","ts":1789457645816,"field":"cvss","old":null,"new":"9.1"},{"seq":203501,"id":"CVE-2026-8927","ts":1789457645816,"field":"severity","old":"none","new":"critical"}]}