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curl CVE-2026-4873

| EUVDEUVD-2026-29922 MEDIUM
Cleartext Transmission of Sensitive Information (CWE-319)
5.9
CVSS 3.1 · NVD
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Severity by source

NVD PRIMARY
5.9 MEDIUM
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
SUSE
MEDIUM
qualitative
Red Hat
5.3 MEDIUM
qualitative

Primary rating from NVD.

CVSS VectorNVD

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

Lifecycle Timeline

3
Analysis Generated
Jun 08, 2026 - 12:07 vuln.today
CVSS changed
May 13, 2026 - 20:22 NVD
5.9 (MEDIUM)
CVE Published
May 08, 2026 - 06:45 nvd
UNKNOWN (no severity yet)

Description PRE-NVD

Disclosed via oss-security. NVD scoring and full description are pending.

AnalysisAI

Connection reuse logic in curl ignores TLS requirements, causing sensitive data to be transmitted in cleartext over channels that should be TLS-encrypted. When curl's connection pool reuses an existing non-encrypted connection to fulfill a subsequent HTTPS request, credentials, tokens, or request payloads may traverse the network without encryption. Affects curl versions 7.20.0 through 8.19.0 (cpe:2.3:a:haxx:curl); no public exploit is identified at time of analysis, SSVC confirms exploitation: none, and EPSS stands at 0.01% (2nd percentile).

Technical ContextAI

curl's connection reuse subsystem - a performance optimization that keeps established connections alive and reuses them for subsequent requests to the same host - fails to validate that a pooled connection satisfies the TLS requirements of an incoming request. CWE-319 (Cleartext Transmission of Sensitive Information) identifies the root cause: sensitive data is transmitted over a channel that should be encrypted but is not, because the connection selection logic does not enforce protocol-level security constraints before reuse. The affected product is cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:* spanning versions 7.20.0 through 8.19.0 per EUVD data, indicating this logic flaw has existed across approximately 15 years of releases. This advisory is one of three related curl connection reuse flaws disclosed simultaneously by Daniel Stenberg (CVE-2026-4873, CVE-2026-5545 for HTTP Negotiate, CVE-2026-5773 for SMB), suggesting a systemic pattern in how curl's connection pool validates protocol security requirements. Note: the 'Buffer Overflow' tag present in the intelligence source is inconsistent with CWE-319 and the CVE description; it should be treated as a data quality artifact in that source and does not reflect the actual vulnerability class.

RemediationAI

Vendor-released patch is confirmed available per the curl official security advisory at https://curl.se/docs/CVE-2026-4873.html; the exact fixed release version number is not specified in the available input data and should be verified directly at that URL before deployment. Red Hat users should apply RHSA-2026:12916 via 'yum update curl' or equivalent package management. SUSE users should apply the appropriate update among SUSE-SU-2026:1717, SUSE-SU-2026:1940, SUSE-SU-2026:21440, or SUSE-SU-2026:21452 depending on their SUSE Linux Enterprise product version. As a compensating control where patching is not immediately feasible, libcurl application developers can set CURLOPT_FORBID_REUSE=1 to force a new connection for each transfer, preventing connection pool reuse entirely - this eliminates the vulnerability but imposes additional TLS handshake latency and connection overhead per request. Command-line curl users can use '--no-keepalive' to achieve similar isolation. Environments running curl within CI/CD pipelines or automated credential-exchange workflows should prioritize patching given the data sensitivity risk.

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Vendor StatusVendor

SUSE

Severity: Medium
Product Status
Container suse/manager/4.3/proxy-httpd:4.3.17.9.76.18 Container suse/manager/4.3/proxy-salt-broker:4.3.17.9.66.20 Container suse/sle-micro-rancher/5.3:latest Container suse/sle-micro-rancher/5.4:5.4.4.5.106 Container suse/sle-micro/5.3/toolbox:16.3-6.11.222 Container suse/sle-micro/5.4/toolbox:16.3-5.19.222 Container suse/sle-micro/5.5/toolbox:16.3-3.12.133 Container suse/sle-micro/base-5.5:2.0.4-5.8.271 Image SLES15-SP4-BYOS Image SLES15-SP4-BYOS-Azure Image SLES15-SP4-BYOS-EC2 Image SLES15-SP4-BYOS-GCE Image SLES15-SP4-CHOST-BYOS Image SLES15-SP4-CHOST-BYOS-Aliyun Image SLES15-SP4-CHOST-BYOS-Azure Image SLES15-SP4-CHOST-BYOS-EC2 Image SLES15-SP4-CHOST-BYOS-GCE Image SLES15-SP4-CHOST-BYOS-SAP-CCloud Image SLES15-SP4-HPC-BYOS Image SLES15-SP4-HPC-BYOS-Azure Image SLES15-SP4-HPC-BYOS-EC2 Image SLES15-SP4-HPC-BYOS-GCE Image SLES15-SP4-HPC-EC2 Image SLES15-SP4-HPC-GCE Image SLES15-SP4-Hardened-BYOS Image SLES15-SP4-Hardened-BYOS-Azure Image SLES15-SP4-Hardened-BYOS-EC2 Image SLES15-SP4-Hardened-BYOS-GCE Image SLES15-SP4-SAP-BYOS Image SLES15-SP4-SAP-BYOS-Azure Image SLES15-SP4-SAP-BYOS-EC2 Image SLES15-SP4-SAP-BYOS-GCE Image SLES15-SP4-SAP-Hardened Image SLES15-SP4-SAP-Hardened-Azure Image SLES15-SP4-SAP-Hardened-BYOS Image SLES15-SP4-SAP-Hardened-BYOS-Azure Image SLES15-SP4-SAP-Hardened-BYOS-EC2 Image SLES15-SP4-SAP-Hardened-BYOS-GCE Image SLES15-SP4-SAP-Hardened-GCE Image SLES15-SP5-BYOS-Azure Image SLES15-SP5-BYOS-EC2 Image SLES15-SP5-BYOS-GCE Image SLES15-SP5-CHOST-BYOS-Aliyun Image SLES15-SP5-CHOST-BYOS-Azure Image SLES15-SP5-CHOST-BYOS-EC2 Image SLES15-SP5-CHOST-BYOS-GCE Image SLES15-SP5-CHOST-BYOS-GDC Image SLES15-SP5-CHOST-BYOS-SAP-CCloud Image SLES15-SP5-EC2 Image SLES15-SP5-GCE Image SLES15-SP5-HPC-BYOS-Azure Image SLES15-SP5-HPC-BYOS-EC2 Image SLES15-SP5-HPC-BYOS-GCE Image SLES15-SP5-Hardened-BYOS-Azure Image SLES15-SP5-Hardened-BYOS-EC2 Image SLES15-SP5-Hardened-BYOS-GCE Image SLES15-SP5-SAP-Azure-3P Image SLES15-SP5-SAP-BYOS-Azure Image SLES15-SP5-SAP-BYOS-EC2 Image SLES15-SP5-SAP-BYOS-GCE Image SLES15-SP5-SAP-Hardened-Azure Image SLES15-SP5-SAP-Hardened-BYOS-Azure Image SLES15-SP5-SAP-Hardened-BYOS-EC2 Image SLES15-SP5-SAP-Hardened-BYOS-GCE Image SLES15-SP5-SAP-Hardened-GCE Affected
Container suse/sl-micro/6.0/baremetal-os-container:2.1.3-6.172 Container suse/sl-micro/6.0/kvm-os-container:2.1.3-6.155 Container suse/sl-micro/6.0/rt-os-container:2.1.3-7.168 Affected
Container suse/sl-micro/6.0/base-os-container:2.1.3-7.139 Container suse/sl-micro/6.0/toolbox:13.2-9.105 Image SL-Micro Affected
Container suse/sl-micro/6.1/baremetal-os-container:2.2.1-7.102 Container suse/sl-micro/6.1/kvm-os-container:2.2.1-5.127 Container suse/sl-micro/6.1/rt-os-container:2.2.1-5.116 Affected
Container suse/sl-micro/6.1/base-os-container:2.2.1-5.126 Image SL-Micro-Azure Image SL-Micro-BYOS-Azure Image SL-Micro-BYOS-EC2 Image SL-Micro-BYOS-GCE Image SL-Micro-EC2 Image SUSE-Multi-Linux-Manager-Proxy-BYOS-Azure Image SUSE-Multi-Linux-Manager-Proxy-BYOS-EC2 Image SUSE-Multi-Linux-Manager-Proxy-BYOS-GCE Image SUSE-Multi-Linux-Manager-Server-Azure-llc Image SUSE-Multi-Linux-Manager-Server-Azure-ltd Image SUSE-Multi-Linux-Manager-Server-BYOS-Azure Image SUSE-Multi-Linux-Manager-Server-BYOS-EC2 Image SUSE-Multi-Linux-Manager-Server-BYOS-GCE Image SUSE-Multi-Linux-Manager-Server-EC2-llc Image SUSE-Multi-Linux-Manager-Server-EC2-ltd Affected

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CVE-2026-4873 vulnerability details – vuln.today

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