---
id: CVE-2025-9086
title: '1'
summary: |-
  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 i…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-125
vendor: haxx
product: curl
affected:
  - 'curl >= 8.13.0, < 8.16.0'
  - debian_linux = 11.0
patched:
  - curl 8.16.0
published: '2025-09-12'
updated: '2026-09-14'
sourceUpdated: '2026-09-14T21:16:59.523'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-9086'
references:
  - url: 'https://curl.se/docs/CVE-2025-9086.html'
    label: 2499f714-1537-4658-8207-48ae4bb9eae9
  - url: 'https://curl.se/docs/CVE-2025-9086.json'
    label: 2499f714-1537-4658-8207-48ae4bb9eae9
  - url: 'https://hackerone.com/reports/3294999'
    label: 2499f714-1537-4658-8207-48ae4bb9eae9
  - url: 'http://www.openwall.com/lists/oss-security/2025/09/10/1'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://lists.debian.org/debian-lts-announce/2026/01/msg00002.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-089022.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-253495.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.01395
epssPercentile: 0.71223
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2025-09-12T17:15:47.921625Z'
ingestedAt: '2026-09-14T21:15:17.560Z'
---

## Overview

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.

## Affected

- `curl >= 8.13.0, < 8.16.0`
- `debian_linux = 11.0`

## Remediation

Upgrade past the affected range:

- `curl 8.16.0`