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 just a slash as path (`path=\"/\",`).
Since this site is not secure, the cookie *should* just 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.
References
| Link | Resource |
|---|---|
| https://curl.se/docs/CVE-2025-9086.html | Vendor Advisory Patch |
| https://curl.se/docs/CVE-2025-9086.json | Vendor Advisory |
| https://hackerone.com/reports/3294999 | Exploit Issue Tracking Third Party Advisory |
| http://www.openwall.com/lists/oss-security/2025/09/10/1 | Mailing List Third Party Advisory Patch |
| https://lists.debian.org/debian-lts-announce/2026/01/msg00002.html | Mailing List Third Party Advisory |
Configurations
History
20 Jan 2026, 14:58
| Type | Values Removed | Values Added |
|---|---|---|
| CWE | CWE-125 | |
| CPE | cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:* cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:* |
|
| First Time |
Debian debian Linux
Haxx curl Debian Haxx |
|
| References | () https://curl.se/docs/CVE-2025-9086.html - Vendor Advisory, Patch | |
| References | () https://curl.se/docs/CVE-2025-9086.json - Vendor Advisory | |
| References | () https://hackerone.com/reports/3294999 - Exploit, Issue Tracking, Third Party Advisory | |
| References | () http://www.openwall.com/lists/oss-security/2025/09/10/1 - Mailing List, Third Party Advisory, Patch | |
| References | () https://lists.debian.org/debian-lts-announce/2026/01/msg00002.html - Mailing List, Third Party Advisory |
08 Jan 2026, 10:15
| Type | Values Removed | Values Added |
|---|---|---|
| Summary | (en) 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 just a slash as path (`path=\"/\",`). Since this site is not secure, the cookie *should* just 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. |
05 Jan 2026, 03:15
| Type | Values Removed | Values Added |
|---|---|---|
| References |
|
04 Nov 2025, 22:16
| Type | Values Removed | Values Added |
|---|---|---|
| References |
|
12 Sep 2025, 18:15
| Type | Values Removed | Values Added |
|---|---|---|
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 7.5 |
12 Sep 2025, 06:15
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2025-09-12 06:15
Updated : 2026-01-20 14:58
NVD link : CVE-2025-9086
Mitre link : CVE-2025-9086
CVE.ORG link : CVE-2025-9086
JSON object : View
Products Affected
debian
- debian_linux
haxx
- curl
CWE
CWE-125
Out-of-bounds Read
