CVE-2026-87863

HSTS response erases persisted entries

View on CVE.org
Published Oct 20, 2026 CVSS 3.1 · 8.1 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

Sign in to view the affected projects.

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
Type Values Removed Values Added
Metrics 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'}

 ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}

cvssV3_1

{'score': 8.1, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'}
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
Type Values Removed Values Added
First Time appeared Curl
Curl curl
Vendors & Products Curl
Curl curl
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
Weaknesses

Sources

Status
PUBLISHED
Assigner
curl
Published
Updated
Oct 30, 2026, 12:04 PM
Reserved
Sep 9, 2026, 1:17 PM

View source JSON

Updated
Oct 30, 2026, 12:03 PM

JSON

Status
Awaiting Analysis
Published
Oct 20, 2026, 9:17 PM
Modified
Oct 30, 2026, 12:16 PM

View source JSON

Severity
Low
Public date
Oct 14, 2026, 12:00 PM

View source Bugzilla JSON

Updated
Oct 30, 2026, 3:00 PM

JSON