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curl CVE-2026-8286

| EUVDEUVD-2026-41503 HIGH
Improper Certificate Validation (CWE-295)
2026-06-24 GHSA-32xh-3x3c-6g6h
Information Disclosure Curl
8.1
CVSS 3.1 · Vendor
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Severity by source

Vendor (CNA) PRIMARY
8.1 HIGH
AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
vuln.today AI
7.4 HIGH

AC:H because it needs a pre-existing live STARTTLS connection with a mismatched TLS config eligible for reuse; PR:N as no auth to the client is required; C:H/I:H from data over an improperly-secured channel, A:N.

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

Primary rating from Vendor (CNA).

CVSS VectorVendor

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

Lifecycle Timeline

5
Analysis Updated
Jul 06, 2026 - 18:41 vuln.today
v3 (cvss_changed)
Analysis Updated
Jul 06, 2026 - 18:41 vuln.today
v2 (cvss_changed)
Re-analysis Queued
Jul 06, 2026 - 18:22 vuln.today
cvss_changed
CVSS changed
Jul 06, 2026 - 18:22 NVD
8.1 (HIGH)
Analysis Generated
Jun 24, 2026 - 18:30 vuln.today

Description PRE-NVD

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

AnalysisAI

Information disclosure and integrity exposure in curl/libcurl occurs when a new transfer that uses STARTTLS to upgrade a connection may reuse an already-established live connection whose TLS configuration does not match the requested one, so data intended for a strictly-configured secure channel can traverse a connection negotiated under different (potentially weaker or unverified) TLS settings. The flaw affects a very wide range of curl releases from 7.30.0 through 8.20.0 and is tagged as Information Disclosure with high confidentiality and integrity impact (CVSS 8.1). …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Application reuses libcurl handle across transfers
Delivery
First STARTTLS transfer opens live connection with lenient TLS
Exploit
New transfer requests stricter TLS config
Execution
Reuse logic wrongly matches mismatched connection
Persist
Data sent over improperly-secured channel
Impact
Confidential data exposed / integrity broken
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Vulnerability AssessmentAI

Exploitation Exploitation requires an application using curl/libcurl that performs multiple transfers over a STARTTLS-upgraded protocol (SMTP, IMAP, POP3, FTP with explicit TLS) while connection reuse is enabled, where a live connection already exists and a subsequent transfer specifies a DIFFERENT (typically stricter) TLS configuration that the reuse-matching logic fails to distinguish. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment Signals are mixed and point to a real but non-urgent priority. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An application uses libcurl to perform several STARTTLS-based transfers (for example an automated SMTP or IMAP client) reusing a single handle; a first transfer establishes a live connection with lenient TLS settings, and a later transfer intended to use strict certificate verification is silently placed on that existing mismatched connection. Sensitive credentials or message data are then transmitted over a channel that does not honor the intended TLS security, exposing them to a network-positioned attacker or to a server that stricter settings would otherwise have rejected. …
Remediation Patch available per vendor advisory: upgrade curl/libcurl to the fixed release published by the curl project (see https://curl.se/docs/CVE-2026-8286.html for the exact patched version; no specific fix version is included in the provided data, so confirm it there rather than assuming one). … Detailed patch versions, workarounds, and compensating controls in full report.
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Recommended ActionAI

Within 24 hours: Audit deployment environments to identify systems running curl/libcurl and document versions in use, prioritizing internet-facing applications and those handling sensitive data. …

Sign in for detailed remediation steps and compensating controls.

Threat intelligence, references, and detailed analysis are available after sign-in.

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SUSE

Severity: Important
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CVE-2026-8286 vulnerability details – vuln.today
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