CVE-2026-87866 - Vulnerability Details - OpenCVE

Description

A flaw was found in curl. This vulnerability allows a malicious server to bypass public key pinning when curl is built with the wolfSSL backend. By presenting a specially crafted certificate with a manipulated validity length field, the attacker can trick curl into improperly re-parsing the certificate and authorizing an invalid key during the Transport Layer Security (TLS) handshake.

Published: n/a

Score: 3.7 Low

EPSS: n/a

KEV: No

Impact:

Action:

Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories

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No CVSS v4.0

Attack Vector Network

Attack Complexity High

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact Low

Availability Impact None

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

References

Link	Providers
https://nvd.nist.gov/vuln/detail/CVE-2026-87866
https://www.cve.org/CVERecord?id=CVE-2026-87866

History

Sat, 17 Oct 2026 00:30:00 +0000

Type	Values Removed	Values Added
Description		A flaw was found in curl. This vulnerability allows a malicious server to bypass public key pinning when curl is built with the wolfSSL backend. By presenting a specially crafted certificate with a manipulated validity length field, the attacker can trick curl into improperly re-parsing the certificate and authorizing an invalid key during the Transport Layer Security (TLS) handshake.
Title		curl: curl: wolfSSL public-key pinning bypass
Weaknesses		CWE-295
References		https://nvd.nist.gov/vuln/detail/CVE-2026-87866 https://www.cve.org/CVERecord?id=CVE-2026-87866
Metrics	threat_severity `None`	cvssV3_1 `{'score': 3.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N'}` threat_severity `Low`

Subscriptions

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MITRE

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Vulnrichment

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NVD

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Redhat

Severity : Low

Publid Date: 2026-10-14T12:00:00Z

Links: CVE-2026-87866 - Bugzilla

OpenCVE Enrichment

Updated: 2026-10-17T02:00:07Z

Weaknesses

CWE-295
Improper Certificate Validation

{"acknowledgement": "Red Hat would like to thank Muhamad Arga Reksapati for reporting this issue.", "bugzilla": {"description": "curl: curl: wolfSSL public-key pinning bypass", "id": "2550677", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2550677"}, "csaw": false, "cvss3": {"cvss3_base_score": "3.7", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N", "status": "draft"}, "cwe": "CWE-295", "details": ["A flaw was found in curl. This vulnerability allows a malicious server to bypass public key pinning when curl is built with the wolfSSL backend. By presenting a specially crafted certificate with a manipulated validity length field, the attacker can trick curl into improperly re-parsing the certificate and authorizing an invalid key during the Transport Layer Security (TLS) handshake."], "name": "CVE-2026-87866", "package_state": [{"cpe": "cpe:/a:redhat:confidential_compute_attestation:1", "fix_state": "Not affected", "package_name": "build-of-trustee/trustee-rhel9", "product_name": "Confidential Compute Attestation"}, {"cpe": "cpe:/a:redhat:confidential_compute_attestation:1", "fix_state": "Not affected", "package_name": "openshift-sandboxed-containers/osc-podvm-payload-rhel9", "product_name": "Confidential Compute Attestation"}, {"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "curl", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "igvm", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "rust", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "s390utils", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "snphost", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "trustee", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "curl", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "curl", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "curl", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "curl", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "rust", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "snphost", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Affected", "package_name": "curl", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Affected", "package_name": "rust", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:jboss_core_services:1", "fix_state": "Not affected", "package_name": "jbcs-httpd24-curl", "product_name": "Red Hat JBoss Core Services"}, {"cpe": "cpe:/a:redhat:satellite:6", "fix_state": "Not affected", "package_name": "foreman", "product_name": "Red Hat Satellite 6"}, {"cpe": "cpe:/a:redhat:satellite:6", "fix_state": "Not affected", "package_name": "openvox-agent", "product_name": "Red Hat Satellite 6"}, {"cpe": "cpe:/a:redhat:satellite:6", "fix_state": "Not affected", "package_name": "puppet-agent", "product_name": "Red Hat Satellite 6"}], "public_date": "2026-10-14T12:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-87866\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-87866"], "statement": "This vulnerability is rated as having a Low severity because standard Red Hat distributions compile curl against OpenSSL rather than wolfSSL, significantly limiting exposure. Exploitation strictly requires applications to link against a wolfSSL-backed build of libcurl and enable pinned public key verification. Furthermore, a successful bypass relies on an attacker providing an intricately crafted certificate accepted by the underlying TLS library, leaving typical client deployments unimpacted.", "threat_severity": "Low"}