bad reuse of HTTP Negotiate connection
Summary
| CVE | CVE-2026-1965 |
|---|---|
| State | PUBLISHED |
| Assigner | curl |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-03-11 11:15:59 UTC |
| Updated | 2026-09-15 07:16:27 UTC |
| Description | libcurl can in some circumstances reuse the wrong connection when asked to do an Negotiate-authenticated HTTP or HTTPS request. libcurl features a pool of recent connections so that subsequent requests can reuse an existing connection to avoid overhead. When reusing a connection a range of criterion must first be met. Due to a logical error in the code, a request that was issued by an application could wrongfully reuse an existing connection to the same server that was authenticated using different credentials. One underlying reason being that Negotiate sometimes authenticates *connections* and not *requests*, contrary to how HTTP is designed to work. An application that allows Negotiate authentication to a server (that responds wanting Negotiate) with `user1:password1` and then does another operation to the same server also using Negotiate but with `user2:password2` (while the previous connection is still alive) - the second request wrongly reused the same connection and since it then sees that the Negotiate negotiation is already made, it sends the request over that connection thinking it uses the user2 credentials when it is in fact still using the connection authenticated for user1... The set of authentication methods to use is set with `CURLOPT_HTTPAUTH`. Applications can disable libcurl's reuse of connections and thus mitigate this problem, by using one of the following libcurl options to alter how connections are or are not reused: `CURLOPT_FRESH_CONNECT`, `CURLOPT_MAXCONNECTS` and `CURLMOPT_MAX_HOST_CONNECTIONS` (if using the curl_multi API). |
Risk And Classification
Primary CVSS: v3.1 6.5 MEDIUM from ADP
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
Problem Types: CWE-305 | CWE-305 Authentication Bypass by Primary Weakness | CWE-305 CWE-305 Authentication Bypass by Primary Weakness
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | ADP | DECLARED | 6.5 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N |
| 3.1 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | Secondary | 6.5 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N |
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
LowPrivileges Required
LowUser Interaction
NoneScope
UnchangedConfidentiality
NoneIntegrity
HighAvailability
NoneCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
NVD Known Affected Configurations (CPE 2.3)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Curl | Curl | affected 7.10.6 8.14.2 semver | Not specified |
| CNA | Curl | Curl | affected 8.15.0 8.16.1 semver | Not specified |
| CNA | Curl | Curl | affected 8.17.0 8.19.0 semver | Not specified |
| CNA | Curl | Curl | affected e56ae1426cb7a0a4a427cf8d6099a821fdaae428 f1a39f221d57354990e3eeeddc3404aede2aff70 git | Not specified |
| CNA | Curl | Curl | affected 8.18.0 | Not specified |
| CNA | Curl | Curl | affected 8.17.0 | Not specified |
| CNA | Curl | Curl | affected 8.16.0 | Not specified |
| CNA | Curl | Curl | affected 8.15.0 | Not specified |
| CNA | Curl | Curl | affected 8.14.1 | Not specified |
| CNA | Curl | Curl | affected 8.14.0 | Not specified |
| CNA | Curl | Curl | affected 8.13.0 | Not specified |
| CNA | Curl | Curl | affected 8.12.1 | Not specified |
| CNA | Curl | Curl | affected 8.12.0 | Not specified |
| CNA | Curl | Curl | affected 8.11.1 | Not specified |
| CNA | Curl | Curl | affected 8.11.0 | Not specified |
| CNA | Curl | Curl | affected 8.10.1 | Not specified |
| CNA | Curl | Curl | affected 8.10.0 | Not specified |
| CNA | Curl | Curl | affected 8.9.1 | Not specified |
| CNA | Curl | Curl | affected 8.9.0 | Not specified |
| CNA | Curl | Curl | affected 8.8.0 | Not specified |
| CNA | Curl | Curl | affected 8.7.1 | Not specified |
| CNA | Curl | Curl | affected 8.7.0 | Not specified |
| CNA | Curl | Curl | affected 8.6.0 | Not specified |
| CNA | Curl | Curl | affected 8.5.0 | Not specified |
| CNA | Curl | Curl | affected 8.4.0 | Not specified |
| CNA | Curl | Curl | affected 8.3.0 | Not specified |
| CNA | Curl | Curl | affected 8.2.1 | Not specified |
| CNA | Curl | Curl | affected 8.2.0 | Not specified |
| CNA | Curl | Curl | affected 8.1.2 | Not specified |
| CNA | Curl | Curl | affected 8.1.1 | Not specified |
| CNA | Curl | Curl | affected 8.1.0 | Not specified |
| CNA | Curl | Curl | affected 8.0.1 | Not specified |
| CNA | Curl | Curl | affected 8.0.0 | Not specified |
| CNA | Curl | Curl | affected 7.88.1 | Not specified |
| CNA | Curl | Curl | affected 7.88.0 | Not specified |
| CNA | Curl | Curl | affected 7.87.0 | Not specified |
| CNA | Curl | Curl | affected 7.86.0 | Not specified |
| CNA | Curl | Curl | affected 7.85.0 | Not specified |
| CNA | Curl | Curl | affected 7.84.0 | Not specified |
| CNA | Curl | Curl | affected 7.83.1 | Not specified |
| CNA | Curl | Curl | affected 7.83.0 | Not specified |
| CNA | Curl | Curl | affected 7.82.0 | Not specified |
| CNA | Curl | Curl | affected 7.81.0 | Not specified |
| CNA | Curl | Curl | affected 7.80.0 | Not specified |
| CNA | Curl | Curl | affected 7.79.1 | Not specified |
| CNA | Curl | Curl | affected 7.79.0 | Not specified |
| CNA | Curl | Curl | affected 7.78.0 | Not specified |
| CNA | Curl | Curl | affected 7.77.0 | Not specified |
| CNA | Curl | Curl | affected 7.76.1 | Not specified |
| CNA | Curl | Curl | affected 7.76.0 | Not specified |
| CNA | Curl | Curl | affected 7.75.0 | Not specified |
| CNA | Curl | Curl | affected 7.74.0 | Not specified |
| CNA | Curl | Curl | affected 7.73.0 | Not specified |
| CNA | Curl | Curl | affected 7.72.0 | Not specified |
| CNA | Curl | Curl | affected 7.71.1 | Not specified |
| CNA | Curl | Curl | affected 7.71.0 | Not specified |
| CNA | Curl | Curl | affected 7.70.0 | Not specified |
| CNA | Curl | Curl | affected 7.69.1 | Not specified |
| CNA | Curl | Curl | affected 7.69.0 | Not specified |
| CNA | Curl | Curl | affected 7.68.0 | Not specified |
| CNA | Curl | Curl | affected 7.67.0 | Not specified |
| CNA | Curl | Curl | affected 7.66.0 | Not specified |
| CNA | Curl | Curl | affected 7.65.3 | Not specified |
| CNA | Curl | Curl | affected 7.65.2 | Not specified |
| CNA | Curl | Curl | affected 7.65.1 | Not specified |
| CNA | Curl | Curl | affected 7.65.0 | Not specified |
| CNA | Curl | Curl | affected 7.64.1 | Not specified |
| CNA | Curl | Curl | affected 7.64.0 | Not specified |
| CNA | Curl | Curl | affected 7.63.0 | Not specified |
| CNA | Curl | Curl | affected 7.62.0 | Not specified |
| CNA | Curl | Curl | affected 7.61.1 | Not specified |
| CNA | Curl | Curl | affected 7.61.0 | Not specified |
| CNA | Curl | Curl | affected 7.60.0 | Not specified |
| CNA | Curl | Curl | affected 7.59.0 | Not specified |
| CNA | Curl | Curl | affected 7.58.0 | Not specified |
| CNA | Curl | Curl | affected 7.57.0 | Not specified |
| CNA | Curl | Curl | affected 7.56.1 | Not specified |
| CNA | Curl | Curl | affected 7.56.0 | Not specified |
| CNA | Curl | Curl | affected 7.55.1 | Not specified |
| CNA | Curl | Curl | affected 7.55.0 | Not specified |
| CNA | Curl | Curl | affected 7.54.1 | Not specified |
| CNA | Curl | Curl | affected 7.54.0 | Not specified |
| CNA | Curl | Curl | affected 7.53.1 | Not specified |
| CNA | Curl | Curl | affected 7.53.0 | Not specified |
| CNA | Curl | Curl | affected 7.52.1 | Not specified |
| CNA | Curl | Curl | affected 7.52.0 | Not specified |
| CNA | Curl | Curl | affected 7.51.0 | Not specified |
| CNA | Curl | Curl | affected 7.50.3 | Not specified |
| CNA | Curl | Curl | affected 7.50.2 | Not specified |
| CNA | Curl | Curl | affected 7.50.1 | Not specified |
| CNA | Curl | Curl | affected 7.50.0 | Not specified |
| CNA | Curl | Curl | affected 7.49.1 | Not specified |
| CNA | Curl | Curl | affected 7.49.0 | Not specified |
| CNA | Curl | Curl | affected 7.48.0 | Not specified |
| CNA | Curl | Curl | affected 7.47.1 | Not specified |
| CNA | Curl | Curl | affected 7.47.0 | Not specified |
| CNA | Curl | Curl | affected 7.46.0 | Not specified |
| CNA | Curl | Curl | affected 7.45.0 | Not specified |
| CNA | Curl | Curl | affected 7.44.0 | Not specified |
| CNA | Curl | Curl | affected 7.43.0 | Not specified |
| CNA | Curl | Curl | affected 7.42.1 | Not specified |
| CNA | Curl | Curl | affected 7.42.0 | Not specified |
| CNA | Curl | Curl | affected 7.41.0 | Not specified |
| CNA | Curl | Curl | affected 7.40.0 | Not specified |
| CNA | Curl | Curl | affected 7.39.0 | Not specified |
| CNA | Curl | Curl | affected 7.38.0 | Not specified |
| CNA | Curl | Curl | affected 7.37.1 | Not specified |
| CNA | Curl | Curl | affected 7.37.0 | Not specified |
| CNA | Curl | Curl | affected 7.36.0 | Not specified |
| CNA | Curl | Curl | affected 7.35.0 | Not specified |
| CNA | Curl | Curl | affected 7.34.0 | Not specified |
| CNA | Curl | Curl | affected 7.33.0 | Not specified |
| CNA | Curl | Curl | affected 7.32.0 | Not specified |
| CNA | Curl | Curl | affected 7.31.0 | Not specified |
| CNA | Curl | Curl | affected 7.30.0 | Not specified |
| CNA | Curl | Curl | affected 7.29.0 | Not specified |
| CNA | Curl | Curl | affected 7.28.1 | Not specified |
| CNA | Curl | Curl | affected 7.28.0 | Not specified |
| CNA | Curl | Curl | affected 7.27.0 | Not specified |
| CNA | Curl | Curl | affected 7.26.0 | Not specified |
| CNA | Curl | Curl | affected 7.25.0 | Not specified |
| CNA | Curl | Curl | affected 7.24.0 | Not specified |
| CNA | Curl | Curl | affected 7.23.1 | Not specified |
| CNA | Curl | Curl | affected 7.23.0 | Not specified |
| CNA | Curl | Curl | affected 7.22.0 | Not specified |
| CNA | Curl | Curl | affected 7.21.7 | Not specified |
| CNA | Curl | Curl | affected 7.21.6 | Not specified |
| CNA | Curl | Curl | affected 7.21.5 | Not specified |
| CNA | Curl | Curl | affected 7.21.4 | Not specified |
| CNA | Curl | Curl | affected 7.21.3 | Not specified |
| CNA | Curl | Curl | affected 7.21.2 | Not specified |
| CNA | Curl | Curl | affected 7.21.1 | Not specified |
| CNA | Curl | Curl | affected 7.21.0 | Not specified |
| CNA | Curl | Curl | affected 7.20.1 | Not specified |
| CNA | Curl | Curl | affected 7.20.0 | Not specified |
| CNA | Curl | Curl | affected 7.19.7 | Not specified |
| CNA | Curl | Curl | affected 7.19.6 | Not specified |
| CNA | Curl | Curl | affected 7.19.5 | Not specified |
| CNA | Curl | Curl | affected 7.19.4 | Not specified |
| CNA | Curl | Curl | affected 7.19.3 | Not specified |
| CNA | Curl | Curl | affected 7.19.2 | Not specified |
| CNA | Curl | Curl | affected 7.19.1 | Not specified |
| CNA | Curl | Curl | affected 7.19.0 | Not specified |
| CNA | Curl | Curl | affected 7.18.2 | Not specified |
| CNA | Curl | Curl | affected 7.18.1 | Not specified |
| CNA | Curl | Curl | affected 7.18.0 | Not specified |
| CNA | Curl | Curl | affected 7.17.1 | Not specified |
| CNA | Curl | Curl | affected 7.17.0 | Not specified |
| CNA | Curl | Curl | affected 7.16.4 | Not specified |
| CNA | Curl | Curl | affected 7.16.3 | Not specified |
| CNA | Curl | Curl | affected 7.16.2 | Not specified |
| CNA | Curl | Curl | affected 7.16.1 | Not specified |
| CNA | Curl | Curl | affected 7.16.0 | Not specified |
| CNA | Curl | Curl | affected 7.15.5 | Not specified |
| CNA | Curl | Curl | affected 7.15.4 | Not specified |
| CNA | Curl | Curl | affected 7.15.3 | Not specified |
| CNA | Curl | Curl | affected 7.15.2 | Not specified |
| CNA | Curl | Curl | affected 7.15.1 | Not specified |
| CNA | Curl | Curl | affected 7.15.0 | Not specified |
| CNA | Curl | Curl | affected 7.14.1 | Not specified |
| CNA | Curl | Curl | affected 7.14.0 | Not specified |
| CNA | Curl | Curl | affected 7.13.2 | Not specified |
| CNA | Curl | Curl | affected 7.13.1 | Not specified |
| CNA | Curl | Curl | affected 7.13.0 | Not specified |
| CNA | Curl | Curl | affected 7.12.3 | Not specified |
| CNA | Curl | Curl | affected 7.12.2 | Not specified |
| CNA | Curl | Curl | affected 7.12.1 | Not specified |
| CNA | Curl | Curl | affected 7.12.0 | Not specified |
| CNA | Curl | Curl | affected 7.11.2 | Not specified |
| CNA | Curl | Curl | affected 7.11.1 | Not specified |
| CNA | Curl | Curl | affected 7.11.0 | Not specified |
| CNA | Curl | Curl | affected 7.10.8 | Not specified |
| CNA | Curl | Curl | affected 7.10.7 | Not specified |
| CNA | Curl | Curl | affected 7.10.6 | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| curl.se/docs/CVE-2026-1965.html | 2499f714-1537-4658-8207-48ae4bb9eae9 | curl.se | Patch, Vendor Advisory |
| curl.se/docs/CVE-2026-1965.json | 2499f714-1537-4658-8207-48ae4bb9eae9 | curl.se | Vendor Advisory |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Zhicheng Chen (en)
CNA: Daniel Stenberg (en)
There are currently no legacy QID mappings associated with this CVE.