CVE-2026-87862

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HSTS Policy Loss in curl Due to Parent Entry Override

Publication date: 2026-10-20

Last updated on: 2026-10-30

Assigner: curl

Description

Importing a `includeSubDomains` parent HSTS entry before a longer-lived child entry, silently drops the child. Consequently, when the parent expires, the child's valid HSTS policy is lost, causing curl to issue unencrypted HTTP requests rather than upgrading to HTTPS.

CVSS Scores

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Meta Information

Published

2026-10-20

Last Modified

2026-10-30

Generated

2026-11-10

AI Q&A

2026-10-21

EPSS Evaluated

2026-11-08

NVD

CVE-2026-87862

Affected Vendors & Products

Vendor	Product	Version / Range
curl	curl	8.22.0
curl	curl	8.21.0
curl	curl	8.20.0
curl	curl	8.19.0
curl	curl	8.18.0
curl	curl	8.17.0
curl	curl	8.16.0
curl	curl	8.15.0
curl	curl	8.14.1
curl	curl	8.14.0
curl	curl	8.13.0
curl	curl	8.12.1
curl	curl	8.12.0
curl	curl	8.11.1
curl	curl	8.11.0

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-201	The code transmits data to another actor, but a portion of the data includes sensitive information that should not be accessible to that actor.

Attack-Flow Graph

Executive Summary

This vulnerability involves HTTP Strict Transport Security (HSTS) policy handling in curl. When a parent HSTS entry with includeSubDomains is imported before a longer-lived child entry, the child's policy is silently dropped. This causes curl to lose the child's valid HSTS policy when the parent expires, leading to unencrypted HTTP requests instead of HTTPS upgrades.

Impact Analysis

This vulnerability may expose your data to interception or manipulation during transit. If curl fails to enforce HTTPS due to the lost HSTS policy, sensitive communications could be sent over unencrypted HTTP, increasing the risk of man-in-the-middle attacks or data breaches.

Compliance Impact

This vulnerability could lead to unencrypted HTTP requests instead of HTTPS, potentially exposing sensitive data in transit. This may violate compliance requirements under GDPR (data encryption) and HIPAA (secure transmission of protected health information).

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