CVE-2024-9681

HSTS subdomain overwrites parent cache entry

View on CVE.org
Published Nov 6, 2024 CVSS 3.1 · 5.9 Medium EPSS 2.0% KEV · Not listed
Description
When curl is asked to use HSTS, the expiry time for a subdomain might
overwrite a parent domain's cache entry, making it end sooner or later than
otherwise intended.

This affects curl using applications that enable HSTS and use URLs with the
insecure `HTTP://` scheme and perform transfers with hosts like
`x.example.com` as well as `example.com` where the first host is a subdomain
of the second host.

(The HSTS cache either needs to have been populated manually or there needs to
have been previous HTTPS accesses done as the cache needs to have entries for
the domains involved to trigger this problem.)

When `x.example.com` responds with `Strict-Transport-Security:` headers, this
bug can make the subdomain's expiry timeout *bleed over* and get set for the
parent domain `example.com` in curl's HSTS cache.

The result of a triggered bug is that HTTP accesses to `example.com` get
converted to HTTPS for a different period of time than what was asked for by
the origin server. If `example.com` for example stops supporting HTTPS at its
expiry time, curl might then fail to access `http://example.com` until the
(wrongly set) timeout expires. This bug can also expire the parent's entry
*earlier*, thus making curl inadvertently switch back to insecure HTTP earlier
than otherwise intended.

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-7104-1 curl vulnerability
History
Type Values Removed Values Added
References
Type Values Removed Values Added
Metrics epss

{'score': 0.00263}

 epss

{'score': 0.003}
Type Values Removed Values Added
Metrics epss

{'score': 0.00255}

 epss

{'score': 0.00263}
Type Values Removed Values Added
References
Type Values Removed Values Added
First Time appeared Haxx
Haxx curl
Weaknesses CWE-697
CPEs cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*
Vendors & Products Haxx
Haxx curl
Type Values Removed Values Added
References
Type Values Removed Values Added
Weaknesses CWE-1025
References
Metrics threat_severity

None

 threat_severity

Low
Type Values Removed Values Added
First Time appeared Curl
Curl curl
CPEs cpe:2.3:a:curl:curl:*:*:*:*:*:*:*:*
Vendors & Products Curl
Curl curl
Metrics cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}
Type Values Removed Values Added
Description When curl is asked to use HSTS, the expiry time for a subdomain might overwrite a parent domain's cache entry, making it end sooner or later than otherwise intended. This affects curl using applications that enable HSTS and use URLs with the insecure `HTTP://` scheme and perform transfers with hosts like `x.example.com` as well as `example.com` where the first host is a subdomain of the second host. (The HSTS cache either needs to have been populated manually or there needs to have been previous HTTPS accesses done as the cache needs to have entries for the domains involved to trigger this problem.) When `x.example.com` responds with `Strict-Transport-Security:` headers, this bug can make the subdomain's expiry timeout *bleed over* and get set for the parent domain `example.com` in curl's HSTS cache. The result of a triggered bug is that HTTP accesses to `example.com` get converted to HTTPS for a different period of time than what was asked for by the origin server. If `example.com` for example stops supporting HTTPS at its expiry time, curl might then fail to access `http://example.com` until the (wrongly set) timeout expires. This bug can also expire the parent's entry *earlier*, thus making curl inadvertently switch back to insecure HTTP earlier than otherwise intended.
Title HSTS subdomain overwrites parent cache entry
References
Earlier changes (5)
Weaknesses

Sources

Status
PUBLISHED
Assigner
curl
Published
Updated
Nov 3, 2025, 8:56 PM
Reserved
Oct 9, 2024, 7:57 AM

View source JSON

Updated
Nov 3, 2025, 8:56 PM

JSON

Status
Modified
Published
Nov 6, 2024, 8:15 AM
Modified
Jun 17, 2026, 8:25 AM

View source JSON

Severity
Low
Public date
Nov 6, 2024, 12:00 AM

View source Bugzilla JSON

No data.