What’s Vulnerable › Vulnerabilities
CVE-2026-87863: HSTS response erases persisted entries
- Severity: high (CVSS 8.1 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.8% 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
An authenticated HTTPS origin can supply an HSTS `max-age` value that the parser accepts, but time serialization later fails to process. On 64-bit systems, extreme max-age values compute an absolute expiry within standard time integer limits that exceeds calendar time structure bounds. During cache saves, the original HSTS file is truncated before writing a temporary replacement; when serialization fails, the temporary file is deleted, leaving an empty or partial cache. Because the save error is silently ignored during cleanup, curl exits successfully despite the data loss.
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-2026-87863.html
- https://curl.se/docs/CVE-2026-87863.json
- https://hackerone.com/reports/3972373
- https://hackerone.com/reports/3972373
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