CVE-2026-86415
auto client cert connection reuse mixup
Description
libcurl's connection cache match function never considers the automatic client certificate option, so a cached, already authenticated Schannel connection can be handed to a transfer that got redirected to a different origin, even though the code explicitly switched off the auto client cert option for that transfer to prevent exactly this.
INFO
Published Date :
Oct. 20, 2026, 9:17 p.m.
Last Modified :
Oct. 30, 2026, 12:16 p.m.
Remotely Exploit :
Yes !
Source :
2499f714-1537-4658-8207-48ae4bb9eae9
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
Solution
- Update libcurl to the latest version.
- Rebuild applications using the updated libcurl.
- Verify client certificate authentication behavior.
- Test secure connection handling after updates.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-86415.
| URL | Resource |
|---|---|
| https://curl.se/docs/CVE-2026-86415.html | |
| https://curl.se/docs/CVE-2026-86415.json | |
| https://hackerone.com/reports/3993870 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-86415 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-86415
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-86415 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-86415 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Oct. 30, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N Added CWE CWE-201 Added SSVC {'id': 'CVE-2026-86415', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-10-30T11:50:55.486110Z'} -
New CVE Received by 2499f714-1537-4658-8207-48ae4bb9eae9
Oct. 20, 2026
Action Type Old Value New Value Added Description libcurl's connection cache match function never considers the automatic client certificate option, so a cached, already authenticated Schannel connection can be handed to a transfer that got redirected to a different origin, even though the code explicitly switched off the auto client cert option for that transfer to prevent exactly this. Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/86xxx/CVE-2026-86415.json">CVE-2026-86415</a> Added Reference https://curl.se/docs/CVE-2026-86415.html Added Reference https://curl.se/docs/CVE-2026-86415.json Added Reference https://hackerone.com/reports/3993870