CVE-2026-87862: HSTS cache import drops longer-lived child

Severity: high (CVSS 8.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.0% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-20 · updated 2026-10-30
Weakness: CWE-201

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.

Affected products

curl: from 8.22.0 through 8.22.0; from 8.21.0 through 8.21.0; from 8.20.0 through 8.20.0; from 8.19.0 through 8.19.0; from 8.18.0 through 8.18.0; from 8.17.0 through 8.17.0

References

https://curl.se/docs/CVE-2026-87862.html
https://curl.se/docs/CVE-2026-87862.json
https://hackerone.com/reports/3972357
https://hackerone.com/reports/3972357

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