bad reuse of HTTP Negotiate connection
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · High · None
- Fix status
- Partial Red Hat: 16 fixed, 11 without a fix
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and Red Hat.
Summary
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).
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| curl | curl | 7.10.6 to before 8.14.2; 8.15.0 to before 8.16.1; 8.17.0 to before 8.19.0 | 8.14.2, 8.16.1, 8.19.0 | Patch available | CNA |
| curl | curl | 8.18.0; 8.17.0; 8.16.0; 8.15.0; 8.14.1; 8.14.0; 8.13.0; 8.12.1; 8.12.0; 8.11.1; 8.11.0; 8.10.1; 8.10.0; 8.9.1; 8.9.0; 8.8.0; 8.7.1; 8.7.0; 8.6.0; 8.5.0; 8.4.0; 8.3.0; 8.2.1; 8.2.0; 8.1.2; 8.1.1; 8.1.0; 8.0.1; 8.0.0; 7.88.1; 7.88.0; 7.87.0; 7.86.0; 7.85.0; 7.84.0; 7.83.1; 7.83.0; 7.82.0; 7.81.0; 7.80.0; 7.79.1; 7.79.0; 7.78.0; 7.77.0; 7.76.1; 7.76.0; 7.75.0; 7.74.0; 7.73.0; 7.72.0; 7.71.1; 7.71.0; 7.70.0; 7.69.1; 7.69.0; 7.68.0; 7.67.0; 7.66.0; 7.65.3; 7.65.2; 7.65.1; 7.65.0; 7.64.1; 7.64.0; 7.63.0; 7.62.0; 7.61.1; 7.61.0; 7.60.0; 7.59.0; 7.58.0; 7.57.0; 7.56.1; 7.56.0; 7.55.1; 7.55.0; 7.54.1; 7.54.0; 7.53.1; 7.53.0; 7.52.1; 7.52.0; 7.51.0; 7.50.3; 7.50.2; 7.50.1; 7.50.0; 7.49.1; 7.49.0; 7.48.0; 7.47.1; 7.47.0; 7.46.0; 7.45.0; 7.44.0; 7.43.0; 7.42.1; 7.42.0; 7.41.0; 7.40.0; 7.39.0; 7.38.0; 7.37.1; 7.37.0; 7.36.0; 7.35.0; 7.34.0; 7.33.0; 7.32.0; 7.31.0; 7.30.0; 7.29.0; 7.28.1; 7.28.0; 7.27.0; 7.26.0; 7.25.0; 7.24.0; 7.23.1; 7.23.0; 7.22.0; 7.21.7; 7.21.6; 7.21.5; 7.21.4; 7.21.3; 7.21.2; 7.21.1; 7.21.0; 7.20.1; 7.20.0; 7.19.7; 7.19.6; 7.19.5; 7.19.4; 7.19.3; 7.19.2; 7.19.1; 7.19.0; 7.18.2; 7.18.1; 7.18.0; 7.17.1; 7.17.0; 7.16.4; 7.16.3; 7.16.2; 7.16.1; 7.16.0; 7.15.5; 7.15.4; 7.15.3; 7.15.2; 7.15.1; 7.15.0; 7.14.1; 7.14.0; 7.13.2; 7.13.1; 7.13.0; 7.12.3; 7.12.2; 7.12.1; 7.12.0; 7.11.2; 7.11.1; 7.11.0; 7.10.8; 7.10.7; 7.10.6 | — | No fix listed | CNA |
- curl Vendorcurl Affected 7.10.6 to before 8.14.2; 8.15.0 to before 8.16.1; 8.17.0 to before 8.19.0 Fixed in 8.14.2, 8.16.1, 8.19.0 Patch available CNA
- curl Vendorcurl Affected 8.18.0; 8.17.0; 8.16.0; 8.15.0; 8.14.1; 8.14.0; 8.13.0; 8.12.1; 8.12.0; 8.11.1; 8.11.0; 8.10.1; 8.10.0; 8.9.1; 8.9.0; 8.8.0; 8.7.1; 8.7.0; 8.6.0; 8.5.0; 8.4.0; 8.3.0; 8.2.1; 8.2.0; 8.1.2; 8.1.1; 8.1.0; 8.0.1; 8.0.0; 7.88.1; 7.88.0; 7.87.0; 7.86.0; 7.85.0; 7.84.0; 7.83.1; 7.83.0; 7.82.0; 7.81.0; 7.80.0; 7.79.1; 7.79.0; 7.78.0; 7.77.0; 7.76.1; 7.76.0; 7.75.0; 7.74.0; 7.73.0; 7.72.0; 7.71.1; 7.71.0; 7.70.0; 7.69.1; 7.69.0; 7.68.0; 7.67.0; 7.66.0; 7.65.3; 7.65.2; 7.65.1; 7.65.0; 7.64.1; 7.64.0; 7.63.0; 7.62.0; 7.61.1; 7.61.0; 7.60.0; 7.59.0; 7.58.0; 7.57.0; 7.56.1; 7.56.0; 7.55.1; 7.55.0; 7.54.1; 7.54.0; 7.53.1; 7.53.0; 7.52.1; 7.52.0; 7.51.0; 7.50.3; 7.50.2; 7.50.1; 7.50.0; 7.49.1; 7.49.0; 7.48.0; 7.47.1; 7.47.0; 7.46.0; 7.45.0; 7.44.0; 7.43.0; 7.42.1; 7.42.0; 7.41.0; 7.40.0; 7.39.0; 7.38.0; 7.37.1; 7.37.0; 7.36.0; 7.35.0; 7.34.0; 7.33.0; 7.32.0; 7.31.0; 7.30.0; 7.29.0; 7.28.1; 7.28.0; 7.27.0; 7.26.0; 7.25.0; 7.24.0; 7.23.1; 7.23.0; 7.22.0; 7.21.7; 7.21.6; 7.21.5; 7.21.4; 7.21.3; 7.21.2; 7.21.1; 7.21.0; 7.20.1; 7.20.0; 7.19.7; 7.19.6; 7.19.5; 7.19.4; 7.19.3; 7.19.2; 7.19.1; 7.19.0; 7.18.2; 7.18.1; 7.18.0; 7.17.1; 7.17.0; 7.16.4; 7.16.3; 7.16.2; 7.16.1; 7.16.0; 7.15.5; 7.15.4; 7.15.3; 7.15.2; 7.15.1; 7.15.0; 7.14.1; 7.14.0; 7.13.2; 7.13.1; 7.13.0; 7.12.3; 7.12.2; 7.12.1; 7.12.0; 7.11.2; 7.11.1; 7.11.0; 7.10.8; 7.10.7; 7.10.6 Fixed in — No fix listed CNA
Remediation
- Fix · CNA curl (curl) Fixed in 8.14.2, 8.16.1, 8.19.0
Red Hat 29 advisories
- RHSA-2026:93454 Released 2026-11-02 · Red Hat rating Importantcurl security update
- Red Hat Enterprise Linux AppStream EUS (v.9.6) libcurl-devel-7.76.1-31.el9_6.4
- Red Hat Enterprise Linux BaseOS EUS (v.9.6) curl-7.76.1-31.el9_6.4, curl-minimal-7.76.1-31.el9_6.4, libcurl-7.76.1-31.el9_6.4 +1
- RHSA-2026:82888 Released 2026-10-14 · Red Hat rating Importantcert-manager Operator for Red Hat OpenShift 1.17.2
- Cert Manager support for Red Hat OpenShift release 1.17 registry.redhat.io/cert-manager/cert-manager-operator-bundle
- RHSA-2026:82857 Released 2026-10-14 · Red Hat rating Importantcert-manager Operator for Red Hat OpenShift 1.18.2
- Cert Manager support for Red Hat OpenShift release 1.18 registry.redhat.io/cert-manager/cert-manager-operator-bundle
Show 26 more Red Hat advisories
- RHSA-2026:82372 Released 2026-10-13 · Red Hat rating Importantcert-manager Operator for Red Hat OpenShift 1.18.2
- Cert Manager support for Red Hat OpenShift release 1.18 registry.redhat.io/cert-manager/cert-manager-operator-rhel9
- RHSA-2026:82354 Released 2026-10-13 · Red Hat rating Importantcert-manager Operator for Red Hat OpenShift 1.18.2
- Cert Manager support for Red Hat OpenShift release 1.18 registry.redhat.io/cert-manager/cert-manager-istio-csr-rhel9
- RHSA-2026:82347 Released 2026-10-13 · Red Hat rating Importantcert-manager Operator for Red Hat OpenShift 1.18.2
- Cert Manager support for Red Hat OpenShift release 1.18 registry.redhat.io/cert-manager/jetstack-cert-manager-acmesolver-rhel9, registry.redhat.io/cert-manager/jetstack-cert-manager-rhel9
- RHSA-2026:82336 Released 2026-10-13 · Red Hat rating Importantcert-manager Operator for Red Hat OpenShift 1.17.1
- Cert Manager support for Red Hat OpenShift release 1.17 registry.redhat.io/cert-manager/cert-manager-istio-csr-rhel9
- RHSA-2026:82322 Released 2026-10-13 · Red Hat rating Importantcert-manager Operator for Red Hat OpenShift 1.17.2
- Cert Manager support for Red Hat OpenShift release 1.17 registry.redhat.io/cert-manager/cert-manager-operator-rhel9
- RHSA-2026:82304 Released 2026-10-13 · Red Hat rating Importantcert-manager Operator for Red Hat OpenShift 1.17.2
- Cert Manager support for Red Hat OpenShift release 1.17 registry.redhat.io/cert-manager/jetstack-cert-manager-acmesolver-rhel9, registry.redhat.io/cert-manager/jetstack-cert-manager-rhel9
- RHSA-2026:77255 Released 2026-10-07 · Red Hat rating ModerateRed Hat Hardened Images RPMs bug fix and enhancement update
- Red Hat Hardened Images curl-8.22.0-1.1.hum1@aarch64, curl-8.22.0-1.1.hum1@s390x, curl-8.22.0-1.1.hum1@src +10
- RHSA-2026:72506 Released 2026-09-28 · Red Hat rating Importantcurl security update
- Red Hat Enterprise Linux AppStream EUS (v. 10.0) libcurl-devel-8.12.1-1.el10_0.10
- Red Hat Enterprise Linux BaseOS EUS (v. 10.0) curl-8.12.1-1.el10_0.10, libcurl-8.12.1-1.el10_0.10, libcurl-minimal-8.12.1-1.el10_0.10
- RHSA-2026:72502 Released 2026-09-28 · Red Hat rating Importantcert-manager Operator for Red Hat OpenShift 1.20.1
- Cert Manager support for Red Hat OpenShift release 1.20 registry.redhat.io/cert-manager/cert-manager-trust-manager-rhel9
- RHSA-2026:72476 Released 2026-09-28 · Red Hat rating Importantcert-manager Operator for Red Hat OpenShift 1.20.1
- Cert Manager support for Red Hat OpenShift release 1.20 registry.redhat.io/cert-manager/cert-manager-operator-rhel9
- RHSA-2026:72475 Released 2026-09-28 · Red Hat rating Importantcert-manager Operator for Red Hat OpenShift 1.20.1
- Cert Manager support for Red Hat OpenShift release 1.20 registry.redhat.io/cert-manager/cert-manager-istio-csr-rhel9
- RHSA-2026:72470 Released 2026-09-28 · Red Hat rating Importantcert-manager Operator for Red Hat OpenShift 1.20.1
- Cert Manager support for Red Hat OpenShift release 1.20 registry.redhat.io/cert-manager/jetstack-cert-manager-acmesolver-rhel9, registry.redhat.io/cert-manager/jetstack-cert-manager-rhel9
- RHSA-2026:72399 Released 2026-09-28 · Red Hat rating Importantcert-manager Operator for Red Hat OpenShift 1.20.1
- Cert Manager support for Red Hat OpenShift release 1.20 registry.redhat.io/cert-manager/cert-manager-operator-rhel9
- RHSA-2026:72395 Released 2026-09-28 · Red Hat rating Importantcert-manager Operator for Red Hat OpenShift 1.20.1
- Cert Manager support for Red Hat OpenShift release 1.20 registry.redhat.io/cert-manager/cert-manager-istio-csr-rhel9
- RHSA-2026:72394 Released 2026-09-28 · Red Hat rating Importantcert-manager Operator for Red Hat OpenShift 1.20.1
- Cert Manager support for Red Hat OpenShift release 1.20 registry.redhat.io/cert-manager/jetstack-cert-manager-rhel9
- RHSA-2026:66018 Released 2026-09-09 · Red Hat rating ImportantRed Hat Update Infrastructure 5.3 security update
- Red Hat Update Infrastructure 5 registry.redhat.io/rhui5/cds-kubernetes-rhel9, registry.redhat.io/rhui5/cds-rhel9, registry.redhat.io/rhui5/haproxy-rhel9 +2
- RHSA-2026:63140 Released 2026-09-03 · Red Hat rating Importantcert-manager Operator for Red Hat OpenShift 1.19.2
- Cert Manager support for Red Hat OpenShift release 1.19 registry.redhat.io/cert-manager/cert-manager-istio-csr-rhel9
- RHSA-2026:63138 Released 2026-09-03 · Red Hat rating Importantcert-manager Operator for Red Hat OpenShift 1.19.2
- Cert Manager support for Red Hat OpenShift release 1.19 registry.redhat.io/cert-manager/jetstack-cert-manager-acmesolver-rhel9, registry.redhat.io/cert-manager/jetstack-cert-manager-rhel9
- RHSA-2026:63135 Released 2026-09-03 · Red Hat rating Importantcert-manager Operator for Red Hat OpenShift 1.19.2
- Cert Manager support for Red Hat OpenShift release 1.19 registry.redhat.io/cert-manager/cert-manager-operator-rhel9
- RHSA-2026:61783 Released 2026-08-31 · Red Hat rating ImportantA Subscription Management tool for finding and reporting Red Hat product usage
- Red Hat Discovery 2 registry.redhat.io/discovery/discovery-server-rhel9, registry.redhat.io/discovery/discovery-ui-rhel9
- RHSA-2026:58981 Released 2026-08-24 · Red Hat rating CriticalRed Hat Update Infrastructure 5.3 Technology Preview security update
- Red Hat Update Infrastructure 5 registry.redhat.io/rhui5/cds-kubernetes-tp-rhel9, registry.redhat.io/rhui5/installer-tp-rhel9, registry.redhat.io/rhui5/rhua-tp-rhel9
- RHSA-2026:56869 Released 2026-08-19 · Red Hat rating ImportantRed Hat JBoss Core Services Apache HTTP Server 2.4.62 SP5 security update
- Red Hat JBoss Core Services 2.4.62.SP5
- RHSA-2026:55439 Released 2026-08-17 · Red Hat rating Importantcurl security update
- Red Hat Enterprise Linux AppStream (v. 9) libcurl-devel-7.76.1-40.el9_8.5
- Red Hat Enterprise Linux BaseOS (v. 9) curl-7.76.1-40.el9_8.5, curl-minimal-7.76.1-40.el9_8.5, libcurl-7.76.1-40.el9_8.5 +1
- RHSA-2026:55450 Released 2026-08-17 · Red Hat rating Importantcurl security update
- Red Hat Enterprise Linux AppStream (v. 10) libcurl-devel-8.12.1-4.el10_2.3
- Red Hat Enterprise Linux BaseOS (v. 10) curl-8.12.1-4.el10_2.3, libcurl-8.12.1-4.el10_2.3, libcurl-minimal-8.12.1-4.el10_2.3
- RHSA-2026:7432 Released 2026-04-10 · Red Hat rating ModerateRed Hat Hardened Images RPMs bug fix and enhancement update
- Red Hat Hardened Images curl-8.19.0-3.1.hum1@aarch64, curl-8.19.0-3.1.hum1@src, curl-8.19.0-3.1.hum1@x86_64 +6
- RHSA-2026:6893 Released 2026-04-07 · Red Hat rating ModerateRed Hat Hardened Images RPMs bug fix and enhancement update
- Red Hat Hardened Images curl-8.19.0-3.hum1@aarch64, curl-8.19.0-3.hum1@src, curl-8.19.0-3.hum1@x86_64 +6
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Release ·
curl 8.14.2, 8.16.1, 8.19.0
4 records Highest priority Priority HIGH 1 HIGH, 1 MEDIUM, 2 LOW
Other records, highest priority first
- TI-2026-03294 use after free in SMB connection reusePriority HIGH 72
- TI-2026-03272 token leak with redirect and netrcPriority MEDIUM 63
- TI-2026-03273 wrong proxy connection reuse with credentialsPriority LOW 35
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Confidential Compute Attestation | Affected | No fix yet: Fix deferred |
| Logging Subsystem for Red Hat OpenShift | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 10 | Affected | No fix yet |
| Red Hat Enterprise Linux 6 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 7 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet |
| Red Hat Enterprise Linux AI (RHEL AI) 3 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Dev Spaces | Affected | No fix yet: Fix deferred |
| Red Hat Trusted Profile Analyzer | Affected | No fix yet: Fix deferred |
| Cert Manager support for Red Hat OpenShift release 1.17 | Fixed | RHSA-2026:82304, RHSA-2026:82322, RHSA-2026:82336, RHSA-2026:82888 |
| Cert Manager support for Red Hat OpenShift release 1.18 | Fixed | RHSA-2026:82347, RHSA-2026:82354, RHSA-2026:82372, RHSA-2026:82857 |
| Cert Manager support for Red Hat OpenShift release 1.19 | Fixed | RHSA-2026:63135, RHSA-2026:63138, RHSA-2026:63140 |
| Cert Manager support for Red Hat OpenShift release 1.20 | Fixed | RHSA-2026:72394, RHSA-2026:72395, RHSA-2026:72399, RHSA-2026:72470, RHSA-2026:72475, RHSA-2026:72476, RHSA-2026:72502 |
| Red Hat Discovery 2 | Fixed | RHSA-2026:61783 |
| Red Hat Enterprise Linux AppStream (v. 10) | Fixed | RHSA-2026:55450 |
| Red Hat Enterprise Linux AppStream (v. 9) | Fixed | RHSA-2026:55439 |
| Red Hat Enterprise Linux AppStream EUS (v. 10.0) | Fixed | RHSA-2026:72506 |
| Red Hat Enterprise Linux AppStream EUS (v.9.6) | Fixed | RHSA-2026:93454 |
| Red Hat Enterprise Linux BaseOS (v. 10) | Fixed | RHSA-2026:55450 |
| Red Hat Enterprise Linux BaseOS (v. 9) | Fixed | RHSA-2026:55439 |
| Red Hat Enterprise Linux BaseOS EUS (v. 10.0) | Fixed | RHSA-2026:72506 |
| Red Hat Enterprise Linux BaseOS EUS (v.9.6) | Fixed | RHSA-2026:93454 |
| Red Hat Hardened Images | Fixed | RHSA-2026:6893, RHSA-2026:7432, RHSA-2026:77255 |
| Red Hat JBoss Core Services 2.4.62.SP5 | Fixed | RHSA-2026:56869 |
| Red Hat Update Infrastructure 5 | Fixed | RHSA-2026:58981, RHSA-2026:66018 |
Not affected: 5 products
- Cert Manager support for Red Hat OpenShift release 1.20
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 9
- Red Hat OpenShift AI (RHOAI)
- Red Hat Update Infrastructure 5
Timeline
- 2026-10-02 Threatist record created from CVE-2026-1965
- 2026-10-03 Alias added: GHSA-q9qg-g2c3-3hr2
- 2026-10-09 Fix available: RHSA-2026:56869 · Red Hat
- 2026-10-09 Fix available: Red Hat JBoss Core Services 2.4.62.SP5 · Red Hat
- 2026-10-12 Fix available: RHSA-2026:77255 · Red Hat
- 2026-10-12 Affected versions changed · Red Hat
- 2026-10-14 Fix available: RHSA-2026:82304 · Red Hat
- 2026-10-14 Fix available: RHSA-2026:82322 · Red Hat
- 2026-10-14 Fix available: RHSA-2026:82336 · Red Hat
- 2026-10-14 Fix available: RHSA-2026:82372 · Red Hat
- 2026-10-14 Fix available: RHSA-2026:82354 · Red Hat
- 2026-10-14 Fix available: RHSA-2026:82347 · Red Hat
- 2026-10-15 Fix available: RHSA-2026:82857 · Red Hat
- 2026-10-15 Fix available: RHSA-2026:82888 · Red Hat
- 2026-10-16 Fix available: RHSA-2026:7432 · Red Hat
- 2026-10-16 Fix available: Cert Manager support for Red Hat OpenShift release 1.17, Cert Manager support for Red Hat OpenShift release 1.18 · Red Hat
- 2026-11-02 Fix available: RHSA-2026:93454 · Red Hat
- 2026-11-02 Fix available: Red Hat Enterprise Linux AppStream EUS (v.9.6), Red Hat Enterprise Linux BaseOS EUS (v.9.6) · Red Hat
- 2026-11-06 Affected versions changed · Red Hat
References
More curl vulnerabilities
- TI-2023-19922 Out-of-bounds write in curl CVSS 3.1CRITICAL 9.8
- TI-2026-16162 Negotiate ambient user conn reuse CVSS 3.1CRITICAL 9.8
- TI-2026-10231 cross-origin Digest auth state leak CVSS 3.1CRITICAL 9.8
- TI-2026-09063 HTTP/2 stream-dependency tree UAF CVSS 3.1CRITICAL 9.8
- TI-2026-07976 stale proxy password leak CVSS 3.1CRITICAL 9.8
- TI-2026-07845 SASL double-free CVSS 3.1CRITICAL 9.8
Sources
- CVE-2026-1965 · CVE Program
- CVE-2026-1965 · NVD
- FIRST EPSS
- GHSA-q9qg-g2c3-3hr2 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-1965 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences