CVE-2025-9086

HIGHCVSS 7.5/10EPSS 1.40%

Last modified

CVE-2025-9086 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 1. A cookie is set using the `secure` keyword for `https://target` 2. EPSS estimates a 1.40% chance of exploitation in the next 30 days.

Description

1. A cookie is set using the `secure` keyword for `https://target` 2. curl is redirected to or otherwise made to speak with `http://target` (same hostname, but using clear text HTTP) using the same cookie set 3. The same cookie name is set - but with only a slash as path (`path="/"`). Since this site is not secure, the cookie *should* be ignored. 4. A bug in the path comparison logic makes curl read outside a heap buffer boundary The bug either causes a crash or it potentially makes the comparison come to the wrong conclusion and lets the clear-text site override the contents of the secure cookie, contrary to expectations and depending on the memory contents immediately following the single-byte allocation that holds the path. The presumed and correct behavior would be to plainly ignore the second set of the cookie since it was already set as secure on a secure host so overriding it on an insecure host should not be okay.

Metrics

EPSS Probability
1.40%

70.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
HaxxCurl>= 8.13.0, < 8.16.0
DebianDebian Linux11.0

References

Timeline

Published
Last Modified
Status
Modified

Frequently Asked Questions

What is CVE-2025-9086?
1. A cookie is set using the `secure` keyword for `https://target` 2. curl is redirected to or otherwise made to speak with `http://target` (same hostname, but using clear text HTTP) using the same cookie set 3. The same cookie name is set - but with only a slash as path (`path="/"`). Since this site is not secure, the cookie *should* be ignored. 4. A bug in the path comparison logic makes curl read outside a heap buffer boundary The bug either causes a crash or it potentially makes the comparison come to the wrong conclusion and lets the clear-text site override the contents of the secure cookie, contrary to expectations and depending on the memory contents immediately following the single-byte allocation that holds the path. The presumed and correct behavior would be to plainly ignore the second set of the cookie since it was already set as secure on a secure host so overriding it on an insecure host should not be okay.
How severe is CVE-2025-9086?
CVE-2025-9086 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 1.40% probability of exploitation in the next 30 days.
How do I fix CVE-2025-9086?
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.

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Source: NVD / NIST