curl up to 8.22.0 Redirect certificate host validation

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
3.7$0-$5k2.43-

Summaryinfo

A vulnerability marked as problematic has been reported in curl. Affected is an unknown function of the component Redirect. The manipulation leads to certificate host validation. This vulnerability is listed as CVE-2026-86410. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in curl. This issue affects an unknown code of the component Redirect. The manipulation with an unknown input leads to a certificate host validation vulnerability. Using CWE to declare the problem leads to CWE-297. The product communicates with a host that provides a certificate, but the product does not properly ensure that the certificate is actually associated with that host. Impacted is integrity. The summary by CVE is:

A flaw in the curl command line tool's logic makes it only set SSH host verification options when interacting directly using SFTP or SCP, and not as a result of following a redirect.

The advisory is shared at curl.se. The identification of this vulnerability is CVE-2026-86410 since 09/07/2026. The exploitation is known to be difficult. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/20/2026). MITRE ATT&CK project uses the attack technique T1587.003 for this issue.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-105275). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 3.7
VulDB Meta Temp Score: 3.7

VulDB Base Score: 3.7
VulDB Temp Score: 3.7
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Certificate host validation
CWE: CWE-297 / CWE-295 / CWE-287
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Timelineinfo

09/07/2026 CVE reserved
10/20/2026 +43 days Advisory disclosed
10/20/2026 +0 days VulDB entry created
10/20/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: curl.se
Status: Confirmed

CVE: CVE-2026-86410 (🔒)
GCVE (CVE): GCVE-0-2026-86410
GCVE (VulDB): GCVE-100-422993
EUVD: 🔒

Entryinfo

Created: 10/20/2026 22:28
Updated: 10/20/2026 23:19
Changes: 10/20/2026 22:28 (52), 10/20/2026 23:19 (1)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Discussion

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