curl: Negotiate Authentication Premature on Connection Reuse

Summary: Curl 8.19.0+ inappropriately sends Negotiate authentication headers on reused keep-alive connections where authentication was already completed. Commit ab650379a8 June 2025 moved negotiate auth context to on-demand metadata storage, but during connection reuse the metadata gets cleared...

curl: curl: Authentication bypass due to incorrect connection reuse with Negotiate authentication

A flaw was found in curl. When an application uses libcurl to make multiple Negotiate-authenticated HTTP or HTTPS requests to the same server with different credentials, libcurl may incorrectly reuse an existing connection. This logical error can cause a subsequent request to be sent using the...

curl: Negotiate connection reuse with wrong credentials when using CURLAUTH_ANY

Summary: CVE-2026-1965 fixed connection reuse for Negotiate authentication by adding urlmatchauthnego in urlmatchconn at line 1244 of lib/url.c. When a first handle authenticates via Negotiate Kerberos on a connection and that connection returns to the pool, a second handle with different...

curl: CVE-2026-5545: wrong reuse of HTTP Negotiate connection

Summary: An attacker sharing a libcurl multi-handle connection pool can hijack another user's Negotiate/Kerberos-authenticated connection. When User A authenticates via Negotiate SPNEGO and the connection returns to the pool, User B using CURLAUTHANY with different credentials gets that connectio...

CLSA-2026-1774260216 Fix CVE(s): CVE-2026-1965, CVE-2026-3783, CVE-2026-3784

SECURITY UPDATE: reuse of connections using HTTP Negotiate - debian/patches/CVE-2026-1965.patch: fix reuse of connections using HTTP Negotiate and fix copy and paste urlmatchauthnego mistake. - CVE-2026-1965 Bearer token sent without checking auth is allowed - debian/patches/CVE-2026-3783.patch:...

CLSA-2026-1774259220 curl: Fix of 3 CVEs

CVE-2026-1965: fix incorrect connection reuse; prevent reuse of Negotiate- authenticated connections with different credentials and require authentication identity match - CVE-2026-3784: fix wrong proxy connection reuse with different credentials; check proxy user/password in proxyinfomatches to...

OESA-2026-1704 curl security update

cURL is a computer software project providing a library libcurl and command-line tool curl for transferring data using various protocols. Security Fixes: libcurl can in some circumstances reuse the wrong connection when asked to do an Negotiate-authenticated HTTP or HTTPS request. libcurl feature...

SUSE-SU-2026:20760-1 Security update for curl

This update for curl fixes the following issues: - CVE-2026-1965: bad reuse of HTTP Negotiate connection bsc1259362. - CVE-2026-3783: token leak with redirect and netrc bsc1259363. - CVE-2026-3784: wrong proxy connection reuse with credentials bsc1259364. - CVE-2026-3805: use after free in SMB...

SUSE-SU-2026:20918-1 Security update for curl

This update for curl fixes the following issues: - CVE-2026-1965: bad reuse of HTTP Negotiate connection bsc1259362. - CVE-2026-3783: token leak with redirect and netrc bsc1259363. - CVE-2026-3784: wrong proxy connection reuse with credentials bsc1259364. - CVE-2026-3805: use after free in SMB...

OPENSUSE-SU-2026:20404-1 Security update for curl

This update for curl fixes the following issues: - CVE-2026-1965: bad reuse of HTTP Negotiate connection bsc1259362. - CVE-2026-3783: token leak with redirect and netrc bsc1259363. - CVE-2026-3784: wrong proxy connection reuse with credentials bsc1259364. - CVE-2026-3805: use after free in SMB...

SUSE SLED15 / SLES15 Security Update : curl (SUSE-SU-2026:0911-1)

The remote SUSE Linux SLED15 / SLEDSAP15 / SLES15 / SLESSAP15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2026:0911-1 advisory. - CVE-2026-1965: bad reuse of HTTP Negotiate connection bsc1259362. - CVE-2026-3783: token leak with redirect...

SUSE SLES12 Security Update : curl (SUSE-SU-2026:0921-1)

The remote SUSE Linux SLES12 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2026:0921-1 advisory. - CVE-2026-1965: bad reuse of HTTP Negotiate connection bsc1259362. - CVE-2026-3783: token leak with redirect and netrc bsc1259363. -...

Security update for curl

This update for curl fixes the following issues: CVE-2026-1965: bad reuse of HTTP Negotiate connection bsc1259362. CVE-2026-3783: token leak with redirect and netrc bsc1259363. CVE-2026-3784: wrong proxy connection reuse with credentials bsc1259364. Patch Instructions: To install this SUSE update...

Security update for curl

This update for curl fixes the following issues: CVE-2026-1965: bad reuse of HTTP Negotiate connection bsc1259362. CVE-2026-3783: token leak with redirect and netrc bsc1259363. CVE-2026-3784: wrong proxy connection reuse with credentials bsc1259364. CVE-2026-3805: use after free in SMB connection...

SUSE-SU-2026:0911-1 Security update for curl

This update for curl fixes the following issues: - CVE-2026-1965: bad reuse of HTTP Negotiate connection bsc1259362. - CVE-2026-3783: token leak with redirect and netrc bsc1259363. - CVE-2026-3784: wrong proxy connection reuse with credentials bsc1259364. - CVE-2026-3805: use after free in SMB...

Security update for curl

This update for curl fixes the following issues: CVE-2026-1965: bad reuse of HTTP Negotiate connection bsc1259362. CVE-2026-3783: token leak with redirect and netrc bsc1259363. CVE-2026-3784: wrong proxy connection reuse with credentials bsc1259364. CVE-2026-3805: use after free in SMB connection...

SUSE-SU-2026:0903-1 Security update for curl

This update for curl fixes the following issues: - CVE-2026-1965: bad reuse of HTTP Negotiate connection bsc1259362. - CVE-2026-3783: token leak with redirect and netrc bsc1259363. - CVE-2026-3784: wrong proxy connection reuse with credentials bsc1259364. - CVE-2026-3805: use after free in SMB...

Ubuntu 18.04 LTS / 20.04 LTS : curl vulnerabilities (USN-8099-1)

The remote Ubuntu 18.04 LTS / 20.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8099-1 advisory. Zhicheng Chen discovered that curl could incorrectly reuse the wrong connection for Negotiate- authenticated HTTP or HTTPS requests. This cou...

Curl 7.10.6 < 8.19.0 Authentication Bypass

The version of curl installed on the remote host is 7.10.6 prior to 8.19.0. It is, therefore, affected by an authentication bypass vulnerability: - libcurl can in some circumstances reuse the wrong connection when asked to do an Negotiate-authenticated HTTP or HTTPS request. libcurl features a po...

Ubuntu: Security Advisory (USN-8099-1)

The remote host is missing an update for the SPDX-FileCopyrightText: 2026 Greenbone AG Some text descriptions might be excerpted from a referenced sources, and are Copyright C by the respective right holders. SPDX-License-Identifier: GPL-2.0-only ifdescription...