CVE-2025-9086

A cookie is set using the secure keyword for https://target
1. curl is redirected to or otherwise made to speak with http://target (same hostname, but using clear text HTTP) using the same cookie set
2. The same cookie name is set - but with just a slash as path (path=\"/\",). Since this site is not secure, the cookie should just be ignored.
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.

References

Affected packages

Git / github.com/curl/curl

Affected ranges

Type

GIT

Repo

https://github.com/curl/curl

Events

Introduced

1c3149881769e7bd79b072e48374e4c2b3678b2f

Fixed

11b991232fbcaa88e2b1faecac224416b0001e35

Database specific

{
    "versions": [
        {
            "introduced": "8.13.0"
        },
        {
            "fixed": "8.16.0"
        }
    ]
}

Affected versions

Other

curl-8_13_0

curl-8_14_0

curl-8_14_1

curl-8_15_0

Database specific

source

"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-9086.json"

unresolved_ranges

[
    {
        "events": [
            {
                "introduced": "0"
            },
            {
                "last_affected": "11.0"
            }
        ]
    }
]