{"id":"CVE-2026-5545","title":"libcurl might in some circumstances reuse the wrong connection when asked to\ndo an authenticated HTTP(S) request after a Negotiate-authenticated one, when\nboth use the same host.\n\nlibcurl features a pool of recent connections so that sub…","summary":"libcurl might in some circumstances reuse the wrong connection when asked to\ndo an authenticated HTTP(S) request after a Negotiate-authenticated one, when\nboth use the same host.\n\nlibcurl features a pool of recent connections so that sub…","severity":"medium","cvss":6.5,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N","cwe":["CWE-305","CWE-613","CWE-488"],"vendor":"haxx","product":"curl","affected":["curl >= 7.10.6, < 8.20.0"],"patched":["curl 8.20.0"],"published":"2026-05-13","updated":"2026-09-15","sourceUpdated":"2026-09-15T07:16:28.633","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-5545","references":[{"url":"https://curl.se/docs/CVE-2026-5545.html","label":"2499f714-1537-4658-8207-48ae4bb9eae9"},{"url":"https://curl.se/docs/CVE-2026-5545.json","label":"2499f714-1537-4658-8207-48ae4bb9eae9"},{"url":"https://hackerone.com/reports/3642555","label":"2499f714-1537-4658-8207-48ae4bb9eae9"},{"url":"https://hackerone.com/reports/3642555","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5545.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-5545"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2461204"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-5545"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-5545"},{"url":"https://access.redhat.com/errata/RHSA-2026:12916"}],"tags":["nvd","cve.org","csaf","vex","red-hat"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-05-13T17:46:36.115262Z"},"epss":0.00414,"epssPercentile":0.3524,"ingestedAt":"2026-09-15T07:33:29.264Z","slug":"CVE-2026-5545","body":"## Overview\n\nlibcurl might in some circumstances reuse the wrong connection when asked to\ndo an authenticated HTTP(S) request after a Negotiate-authenticated one, when\nboth use the same host.\n\nlibcurl features a pool of recent connections so that subsequent requests can\nreuse an existing connection to avoid overhead.\n\nWhen reusing a connection a range of criteria must be met. Due to a logical\nerror in the code, a request that was issued by an application could\nwrongfully reuse an existing connection to the same server that was\nauthenticated using different credentials.\n\nAn application that first uses Negotiate authentication to a server with\n`user1:password1` and then does another operation to the same server asking\nfor any authentication method but for `user2:password2` (while the previous\nconnection is still alive) - the second request gets confused and wrongly\nreuses the same connection and sends the new request over that connection\nthinking it uses a mix of user1's and user2's credentials when it is in fact\nstill using the connection authenticated for user1...\n\n## Affected\n\n- `curl >= 7.10.6, < 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- **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 2026-09-15 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5545.json)","depth":"sunlit","depthScore":36,"depthScoreParts":{"impact":35.8,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}