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libcurl EUVDEUVD-2026-72166

| CVE-2026-19931 CRITICAL
Exposure of Data Element to Wrong Session (CWE-488)
Critical
Disputed · 9.8 Vendor
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Severity by source

Sources disagree (Medium–Critical)
Vendor (CNA) PRIMARY
9.8 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vuln.today AI
6.5 MEDIUM

AC:H because it needs a shared multi-user libcurl context, Negotiate auth, an empty-credential initial request, and reuse timing; primary impact is confidentiality (C:H), a request under another's identity gives limited I:L, and no availability impact (A:N).

3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N
4.0 AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N
SUSE
5.9 MEDIUM
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

vuln.today treats the vendor’s rating as authoritative. A higher third-party CVSS (e.g. CISA-ADP) is shown for transparency but does not drive the headline severity.

CVSS VectorVendor

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

5
Analysis Updated
Sep 08, 2026 - 16:30 vuln.today
v2 (cvss_changed)
Re-analysis Queued
Sep 08, 2026 - 16:22 vuln.today
cvss_changed
CVSS changed
Sep 08, 2026 - 16:22 NVD
9.8 (CRITICAL)
Analysis Generated
Sep 02, 2026 - 12:20 vuln.today
CVE Published
Sep 02, 2026 - 10:57 oss-security
CRITICAL

Description PRE-NVD

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

AnalysisAI

Cross-user session confusion in libcurl allows one user's HTTP request to be silently transmitted over another user's previously authenticated Negotiate (SPNEGO/Kerberos) connection. When an initial request to a host is made with empty credentials, libcurl incorrectly treats the resulting connection as eligible for reuse, so a subsequent request from a different principal inherits the earlier authenticated context. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
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Delivery
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Exploit
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Execution
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Persist
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Impact
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Vulnerability AssessmentAI

Exploitation Requires a deployment where a single libcurl instance/connection cache is shared across multiple users or requests (e.g., a proxy, gateway, or multi-tenant service), the target host uses HTTP Negotiate (SPNEGO/Kerberos) authentication, and an initial request to that hostname is issued with empty credentials - that empty-credential initial request is the exact trigger that makes libcurl wrongly mark the connection reusable. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The input CVSS of 9.8 (AV:N/AC:L/PR:N/UI:N/C:H/I:H/A:H) substantially overstates real-world risk and is internally inconsistent with the described mechanism. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario Full exploit scenario with step-by-step reproduction available after sign-in.
Remediation Patch available per vendor advisory (https://curl.se/docs/CVE-2026-19931.html); the exact fixed release is not stated in the provided data, so confirm the patched version directly from the curl advisory before pinning (affected range extends through 8.21.0, so the fix is in the subsequent release). … Detailed patch versions, workarounds, and compensating controls in full report.

Recommended ActionAI

Within 24 hours: Identify all applications and systems using libcurl, particularly those in multi-user or proxy deployments that reuse libcurl handles across different principals. …

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
openSUSE Tumbleweed Fixed
SLES15-SP5-CHOST-BYOS-SAP-CCloud Affected
SLES15-SP6-CHOST-BYOS Affected
SLES15-SP6-CHOST-BYOS-Aliyun Affected
SLES15-SP6-CHOST-BYOS-Azure Affected

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EUVD-2026-72166 vulnerability details – vuln.today

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