{"id":"CVE-2026-6253","title":"curl might erroneously pass on credentials for a first proxy to a second\nproxy.\n\nThis can happen when the following conditions are true:\n\n1","summary":"curl might erroneously pass on credentials for a first proxy to a second\nproxy.\n\nThis can happen when the following conditions are true:\n\n1. curl is setup to use specific different proxies for different URL schemes\n2. the first proxy nee…","severity":"medium","cvss":5.9,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-522","CWE-201"],"vendor":"haxx","product":"curl","affected":["curl >= 7.14.1, < 8.20.0"],"patched":["curl 8.20.0"],"published":"2026-05-13","updated":"2026-09-15","sourceUpdated":"2026-09-15T07:16:29.073","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-6253","references":[{"url":"https://curl.se/docs/CVE-2026-6253.html","label":"2499f714-1537-4658-8207-48ae4bb9eae9"},{"url":"https://curl.se/docs/CVE-2026-6253.json","label":"2499f714-1537-4658-8207-48ae4bb9eae9"},{"url":"https://hackerone.com/reports/3669637","label":"2499f714-1537-4658-8207-48ae4bb9eae9"},{"url":"http://www.openwall.com/lists/oss-security/2026/04/29/11","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://hackerone.com/reports/3669637","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-6253.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-6253"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2461202"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-6253"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-6253"},{"url":"https://access.redhat.com/errata/RHSA-2026:12916"},{"url":"https://access.redhat.com/errata/RHSA-2026:56869"}],"tags":["nvd","cve.org","exploit-available","csaf","vex","red-hat"],"exploitAvailable":true,"ssvc":{"exploitation":"poc","automatable":"no","technicalImpact":"partial","timestamp":"2026-05-13T17:42:30.813126Z"},"epss":0.00719,"epssPercentile":0.52015,"ingestedAt":"2026-09-15T07:33:29.265Z","scores":{"nvd":5.9,"vendor":5.3},"slug":"CVE-2026-6253","body":"## Overview\n\ncurl might erroneously pass on credentials for a first proxy to a second\nproxy.\n\nThis can happen when the following conditions are true:\n\n1. curl is setup to use specific different proxies for different URL schemes\n2. the first proxy needs credentials\n3. the second proxy uses no credentials\n4. while using the first proxy (using say `http://`), curl is asked to follow\n   a redirect to a URL using another scheme (say `https://`), accessed using a\n   second, different, proxy\n\n## Affected\n\n- `curl >= 7.14.1, < 8.20.0`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `curl 8.20.0`\n\n## Vendor advisories\n\n- **RHSA-2026:12916** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-05-02 · [advisory](https://access.redhat.com/errata/RHSA-2026:12916)\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** · Moderate · affected: Confidential Compute Attestation, Logging Subsystem for Red Hat OpenShift, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, … · no fix planned: Confidential Compute Attestation, Logging Subsystem for Red Hat OpenShift, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, … · updated 2026-09-18 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-6253.json)","depth":"twilight","depthScore":45,"depthScoreParts":{"impact":32.5,"likelihood":0.1,"exploitation":12,"ransomware":0},"changes":[]}