CVE-2026-12064
proto-default skips SSH verification
Description
When a user invokes curl using a schemeless URL combined with `--proto-default` sftp (or scp), a disconnect occurs between the tool layer and libcurl. The tool layer incorrectly infers the URL scheme, which erroneously bypasses the initialization of critical SSH security options like CURLOPT_SSH_HOST_PUBLIC_KEY_SHA256 and CURLOPT_SSH_KNOWNHOSTS. Conversely, the libcurl runtime successfully honors CURLOPT_DEFAULT_PROTOCOL and establishes the connection via SFTP/SCP as specified. Because the tool layer skipped the security configuration, these SSH host verification options are silently omitted, causing curl to connect to an unverified SSH remote host without throwing an error.
INFO
Published Date :
July 3, 2026, 7:16 a.m.
Last Modified :
July 7, 2026, 7:43 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 curl to a version that corrects protocol handling.
- Configure explicit SSH host verification options.
- Verify SSH host keys before establishing connections.
- Avoid using schemeless URLs with --proto-default.
Public PoC/Exploit Available at Github
CVE-2026-12064 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
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-2026-12064.
| URL | Resource |
|---|---|
| https://curl.se/docs/CVE-2026-12064.html | Patch Vendor Advisory |
| https://curl.se/docs/CVE-2026-12064.json | Vendor Advisory |
| https://hackerone.com/reports/3797526 | Exploit Issue Tracking Third Party Advisory |
| https://hackerone.com/reports/3797526 | Exploit Issue Tracking Third Party Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-12064 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-2026-12064
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).
AI-powered security report summarizer using Python, AWS Bedrock, Docker and Trivy.
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Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-12064 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-12064 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.
-
Initial Analysis by [email protected]
Jul. 07, 2026
Action Type Old Value New Value Added CWE CWE-295 Added CPE Configuration OR *cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:* versions from (including) 7.81.0 up to (excluding) 8.21.0 Added Reference Type curl: https://curl.se/docs/CVE-2026-12064.html Types: Patch, Vendor Advisory Added Reference Type curl: https://curl.se/docs/CVE-2026-12064.json Types: Vendor Advisory Added Reference Type curl: https://hackerone.com/reports/3797526 Types: Exploit, Issue Tracking, Third Party Advisory Added Reference Type CISA-ADP: https://hackerone.com/reports/3797526 Types: Exploit, Issue Tracking, Third Party Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 06, 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 Reference https://hackerone.com/reports/3797526 Added SSVC {'id': 'CVE-2026-12064', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-07-06T18:19:34.951461Z'} -
New CVE Received by 2499f714-1537-4658-8207-48ae4bb9eae9
Jul. 03, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'curl', 'product': 'curl', 'versions': [{'status': 'affected', 'version': '8.20.0', 'versionType': 'semver', 'lessThanOrEqual': '8.20.0'}, {'status': 'affected', 'version': '8.19.0', 'versionType': 'semver', 'lessThanOrEqual': '8.19.0'}, {'status': 'affected', 'version': '8.18.0', 'versionType': 'semver', 'lessThanOrEqual': '8.18.0'}, {'status': 'affected', 'version': '8.17.0', 'versionType': 'semver', 'lessThanOrEqual': '8.17.0'}, {'status': 'affected', 'version': '8.16.0', 'versionType': 'semver', 'lessThanOrEqual': '8.16.0'}, {'status': 'affected', 'version': '8.15.0', 'versionType': 'semver', 'lessThanOrEqual': '8.15.0'}, {'status': 'affected', 'version': '8.14.1', 'versionType': 'semver', 'lessThanOrEqual': '8.14.1'}, {'status': 'affected', 'version': '8.14.0', 'versionType': 'semver', 'lessThanOrEqual': '8.14.0'}, {'status': 'affected', 'version': '8.13.0', 'versionType': 'semver', 'lessThanOrEqual': '8.13.0'}, {'status': 'affected', 'version': '8.12.1', 'versionType': 'semver', 'lessThanOrEqual': '8.12.1'}, {'status': 'affected', 'version': '8.12.0', 'versionType': 'semver', 'lessThanOrEqual': '8.12.0'}, {'status': 'affected', 'version': '8.11.1', 'versionType': 'semver', 'lessThanOrEqual': '8.11.1'}, {'status': 'affected', 'version': '8.11.0', 'versionType': 'semver', 'lessThanOrEqual': '8.11.0'}, {'status': 'affected', 'version': '8.10.1', 'versionType': 'semver', 'lessThanOrEqual': '8.10.1'}, {'status': 'affected', 'version': '8.10.0', 'versionType': 'semver', 'lessThanOrEqual': '8.10.0'}, {'status': 'affected', 'version': '8.9.1', 'versionType': 'semver', 'lessThanOrEqual': '8.9.1'}, {'status': 'affected', 'version': '8.9.0', 'versionType': 'semver', 'lessThanOrEqual': '8.9.0'}, {'status': 'affected', 'version': '8.8.0', 'versionType': 'semver', 'lessThanOrEqual': '8.8.0'}, {'status': 'affected', 'version': '8.7.1', 'versionType': 'semver', 'lessThanOrEqual': '8.7.1'}, {'status': 'affected', 'version': '8.7.0', 'versionType': 'semver', 'lessThanOrEqual': '8.7.0'}, {'status': 'affected', 'version': '8.6.0', 'versionType': 'semver', 'lessThanOrEqual': '8.6.0'}, {'status': 'affected', 'version': '8.5.0', 'versionType': 'semver', 'lessThanOrEqual': '8.5.0'}, {'status': 'affected', 'version': '8.4.0', 'versionType': 'semver', 'lessThanOrEqual': '8.4.0'}, {'status': 'affected', 'version': '8.3.0', 'versionType': 'semver', 'lessThanOrEqual': '8.3.0'}, {'status': 'affected', 'version': '8.2.1', 'versionType': 'semver', 'lessThanOrEqual': '8.2.1'}, {'status': 'affected', 'version': '8.2.0', 'versionType': 'semver', 'lessThanOrEqual': '8.2.0'}, {'status': 'affected', 'version': '8.1.2', 'versionType': 'semver', 'lessThanOrEqual': '8.1.2'}, {'status': 'affected', 'version': '8.1.1', 'versionType': 'semver', 'lessThanOrEqual': '8.1.1'}, {'status': 'affected', 'version': '8.1.0', 'versionType': 'semver', 'lessThanOrEqual': '8.1.0'}, {'status': 'affected', 'version': '8.0.1', 'versionType': 'semver', 'lessThanOrEqual': '8.0.1'}, {'status': 'affected', 'version': '8.0.0', 'versionType': 'semver', 'lessThanOrEqual': '8.0.0'}, {'status': 'affected', 'version': '7.88.1', 'versionType': 'semver', 'lessThanOrEqual': '7.88.1'}, {'status': 'affected', 'version': '7.88.0', 'versionType': 'semver', 'lessThanOrEqual': '7.88.0'}, {'status': 'affected', 'version': '7.87.0', 'versionType': 'semver', 'lessThanOrEqual': '7.87.0'}, {'status': 'affected', 'version': '7.86.0', 'versionType': 'semver', 'lessThanOrEqual': '7.86.0'}, {'status': 'affected', 'version': '7.85.0', 'versionType': 'semver', 'lessThanOrEqual': '7.85.0'}, {'status': 'affected', 'version': '7.84.0', 'versionType': 'semver', 'lessThanOrEqual': '7.84.0'}, {'status': 'affected', 'version': '7.83.1', 'versionType': 'semver', 'lessThanOrEqual': '7.83.1'}, {'status': 'affected', 'version': '7.83.0', 'versionType': 'semver', 'lessThanOrEqual': '7.83.0'}, {'status': 'affected', 'version': '7.82.0', 'versionType': 'semver', 'lessThanOrEqual': '7.82.0'}, {'status': 'affected', 'version': '7.81.0', 'versionType': 'semver', 'lessThanOrEqual': '7.81.0'}], 'defaultStatus': 'unaffected'}] Added Description When a user invokes curl using a schemeless URL combined with `--proto-default` sftp (or scp), a disconnect occurs between the tool layer and libcurl. The tool layer incorrectly infers the URL scheme, which erroneously bypasses the initialization of critical SSH security options like CURLOPT_SSH_HOST_PUBLIC_KEY_SHA256 and CURLOPT_SSH_KNOWNHOSTS. Conversely, the libcurl runtime successfully honors CURLOPT_DEFAULT_PROTOCOL and establishes the connection via SFTP/SCP as specified. Because the tool layer skipped the security configuration, these SSH host verification options are silently omitted, causing curl to connect to an unverified SSH remote host without throwing an error. Added Reference https://curl.se/docs/CVE-2026-12064.html Added Reference https://curl.se/docs/CVE-2026-12064.json Added Reference https://hackerone.com/reports/3797526