CVE-2026-87863

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.

EPSS

0.2% chance of exploitation in the next 30 days; higher than 12% of CVEs (scores of 2026-10-25)

Published

2026-10-20

Modified

2026-10-22

Record from

the NVD, synced 2026-10-23

References

• https://curl.se/docs/CVE-2026-87863.html
• https://curl.se/docs/CVE-2026-87863.json
• https://hackerone.com/reports/3972373

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