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libcurl EUVDEUVD-2026-41501

| CVE-2026-11856 CRITICAL
Authentication Bypass by Capture-replay (CWE-294)
2026-06-24 GHSA-9crq-qh8v-6xmm
Information Disclosure Curl Red Hat
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
5.9 MEDIUM

Requires the specific handle-reuse and origin-change sequence with Digest auth, so AC:H; impact is credential disclosure only, hence C:H with I:N/A:N, unlike the inflated 9.8.

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

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

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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
Jul 06, 2026 - 19:34 vuln.today
v3 (cvss_changed)
Analysis Updated
Jul 06, 2026 - 19:34 vuln.today
v2 (cvss_changed)
Re-analysis Queued
Jul 06, 2026 - 19:22 vuln.today
cvss_changed
CVSS changed
Jul 06, 2026 - 19:22 NVD
9.8 (CRITICAL)
Analysis Generated
Jun 24, 2026 - 18:32 vuln.today

Description PRE-NVD

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

AnalysisAI

Cross-origin credential leakage in libcurl (curl 7.10.6 through 8.20.0) causes the HTTP Digest 'Authorization:' header computed for one origin (hostA) to be wrongly reused on a subsequent transfer to a different origin (hostB) when an application reuses the same easy handle. This exposes Digest authentication credentials to an unintended, potentially attacker-controlled host, and is tracked as an Information Disclosure issue (EUVD-2026-41501). …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Identify app reusing curl handle
Delivery
Induce second transfer to attacker origin hostB
Exploit
libcurl reattaches hostA Digest header
Execution
Capture leaked Authorization credentials
Impact
Replay credentials against hostA
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Vulnerability AssessmentAI

Exploitation Exploitation requires an application built on libcurl to (1) perform an HTTP transfer to origin hostA using Digest authentication, (2) reuse the same libcurl easy handle without resetting auth state, and (3) issue a second transfer whose origin is changed to hostB, where hostB is attacker-controlled or attacker-influenced (e.g., via a dynamic or user-controlled URL or redirect). … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The published CVSS 3.1 base score of 9.8 (AV:N/AC:L/PR:N/UI:N/C:H/I:H/A:H) substantially overstates real-world risk and is inconsistent with the described behavior: this is a confidentiality-only credential leak, so the Integrity:H and Availability:H metrics are not supported by the description, and AC:L ignores the required precondition that an application reuse the same handle across two different origins with Digest auth on the first. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An application uses one reused libcurl handle to first authenticate to a trusted service (hostA) with Digest credentials, then makes a second request to a different host (hostB) that an attacker controls or can influence (e.g., via a user-supplied URL, redirect, or SSRF-style flow). libcurl attaches hostA's 'Authorization:' header to the hostB request, handing the attacker the Digest credential material. …
Remediation Upgrade libcurl to the fixed release published in the curl project advisory at https://curl.se/docs/CVE-2026-11856.html; the input data does not include a confirmed exact fix version, so verify the patched version directly from that advisory before deploying (no vendor-released patch version is independently confirmed from the provided data - do not assume a version number). … Detailed patch versions, workarounds, and compensating controls in full report.
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Recommended ActionAI

Within 24 hours: Audit production systems to identify all applications running curl 7.10.6-8.20.0, especially those connecting to multiple external services or APIs. …

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Same weakness CWE-294 – Authentication Bypass by Capture-replay

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Same technique Information Disclosure

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CVE-2017-5638 CRITICAL POC
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CVE-2025-24813 CRITICAL POC
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CVE-2015-1701 HIGH POC
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CVE-2017-0147 HIGH POC
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CVE-2014-6324 HIGH POC
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CVE-2023-7028 CRITICAL POC
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CVE-2017-0213 HIGH POC
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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
SLES15-SP5-CHOST-BYOS-SAP-CCloud Affected
SLES15-SP6-CHOST-BYOS Affected
SLES15-SP6-CHOST-BYOS-Aliyun Affected
SLES15-SP6-CHOST-BYOS-Azure Affected
SLES15-SP6-CHOST-BYOS-EC2 Affected

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EUVD-2026-41501 vulnerability details – vuln.today
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