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CVE-2024-9681

MEDIUMCVSS 6.5/10EPSS 1.97%

Last modified

CVE-2024-9681 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. 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. EPSS estimates a 1.97% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
6.5/10

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:L

EPSS Probability
1.97%

77.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
HaxxCurl>= 7.74.0, < 8.11.0

References

Timeline

Published
Last Modified
Status
Modified

Frequently Asked Questions

What is CVE-2024-9681?
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.
How severe is CVE-2024-9681?
CVE-2024-9681 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 1.97% probability of exploitation in the next 30 days.
How do I fix CVE-2024-9681?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2024-9681?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST