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.
Published: 2026-10-20
Score: 3.7 Low
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Ubuntu USN Ubuntu USN USN-8927-1 curl vulnerabilities
Ubuntu USN Ubuntu USN USN-8932-1 curl vulnerabilities
Ubuntu USN Ubuntu USN USN-8927-2 curl vulnerabilities
History

Tue, 20 Oct 2026 20:30:00 +0000

Type Values Removed Values Added
Description A flaw was found in curl. When persistent HTTP Strict Transport Security (HSTS) caching is enabled, a remote HTTPS server can return an out-of-range expiration value that fails time serialization during cache saving. Because curl truncates the cache file prior to writing the update, this serialization failure causes the persistent HSTS cache to be deleted or emptied. As a result, stored security policies for known hosts are lost, potentially allowing future connections to fall back to insecure communication. 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.
Title curl: curl: Hsts Response Erases Persisted Entries HSTS response erases persisted entries
References

Sun, 18 Oct 2026 15:00:00 +0000

Type Values Removed Values Added
First Time appeared Curl
Curl curl
Vendors & Products Curl
Curl curl

Sat, 17 Oct 2026 00:30:00 +0000

Type Values Removed Values Added
Description A flaw was found in curl. When persistent HTTP Strict Transport Security (HSTS) caching is enabled, a remote HTTPS server can return an out-of-range expiration value that fails time serialization during cache saving. Because curl truncates the cache file prior to writing the update, this serialization failure causes the persistent HSTS cache to be deleted or emptied. As a result, stored security policies for known hosts are lost, potentially allowing future connections to fall back to insecure communication.
Title curl: curl: Hsts Response Erases Persisted Entries
Weaknesses CWE-201
References
Metrics threat_severity

None

 cvssV3_1

{'score': 3.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N'}

threat_severity

Low

Subscriptions

Curl Curl
cve-icon MITRE

Status: PUBLISHED

Assigner: curl

Published:

Updated: 2026-10-20T20:13:22.379Z

Reserved: 2026-09-09T13:17:38.076Z

Link: CVE-2026-87863

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-20T21:17:20.380

Modified: 2026-10-20T21:17:20.380

Link: CVE-2026-87863

cve-icon Redhat

Severity : Low

Publid Date: 2026-10-14T12:00:00Z

Links: CVE-2026-87863 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-10-20T22:30:18Z

Weaknesses