cURL up to 8.20.0 certificate host validation

Summaryinfo

A vulnerability has been found in cURL and classified as problematic. This vulnerability affects unknown code. Performing a manipulation results in certificate host validation. This vulnerability is identified as CVE-2026-9547. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in cURL. It has been classified as problematic. This affects an unknown part. The manipulation with an unknown input leads to a certificate host validation vulnerability. CWE is classifying the issue as CWE-297. The product communicates with a host that provides a certificate, but the product does not properly ensure that the certificate is actually associated with that host. This is going to have an impact on integrity. The summary by CVE is:

When a libcurl-based application performs transfers via `SCP://` or `SFTP://` and utilizes the `CURLOPT_SSH_KEYFUNCTION` callback, it may silently accept an untrusted server. This vulnerability occurs when a server presents a host key type that does not match the specific key type already recorded for that host in the `known_hosts` file. Instead of rejecting the mismatch, the callback mechanism fails to properly enforce the restriction, allowing the connection to succeed without warning and risking a potential man-in-the-middle attack.

The weakness was released by Joshua Rogers. It is possible to read the advisory at curl.se. This vulnerability is uniquely identified as CVE-2026-9547 since 05/26/2026. The exploitability is told to be difficult. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/03/2026). The attack technique deployed by this issue is T1587.003 according to MITRE ATT&CK.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-41495). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Type

• Network Utility Software

Name

• cURL

Version

• 7.0
• 7.1
• 7.2
• 7.3
• 7.4
• 7.5
• 7.6
• 7.7
• 7.8
• 7.9
• 7.10
• 7.11
• 7.12
• 7.13
• 7.14
• 7.15
• 7.16
• 7.17
• 7.18
• 7.19
• 7.20
• 7.21
• 7.22
• 7.23
• 7.24
• 7.25
• 7.26
• 7.27
• 7.28
• 7.29
• 7.30
• 7.31
• 7.32
• 7.33
• 7.34
• 7.35
• 7.36
• 7.37
• 7.38
• 7.39
• 7.40
• 7.41
• 7.42
• 7.43
• 7.44
• 7.45
• 7.46
• 7.47
• 7.48
• 7.49
• 7.50
• 7.51
• 7.52
• 7.53
• 7.54
• 7.55
• 7.56
• 7.57
• 7.58
• 7.59
• 7.60
• 7.61
• 7.62
• 7.63
• 7.64
• 7.65
• 7.66
• 7.67
• 7.68
• 7.69
• 7.69.0
• 7.69.1
• 7.70
• 7.70.0
• 7.71
• 7.71.0
• 7.71.1
• 7.72
• 7.72.0
• 7.73
• 7.73.0
• 7.74
• 7.74.0
• 7.75
• 7.75.0
• 7.76
• 7.76.0
• 7.76.1
• 7.77
• 7.77.0
• 7.78
• 7.78.0
• 7.79
• 7.79.0
• 7.79.1
• 7.80
• 7.80.0
• 7.81
• 7.81.0
• 7.82
• 7.82.0
• 7.83
• 7.83.0
• 7.83.1
• 7.84
• 7.84.0
• 7.85
• 7.85.0
• 7.86
• 7.86.0
• 7.87
• 7.87.0
• 7.88.0
• 7.88.1
• 8.0
• 8.0.0
• 8.0.1
• 8.1
• 8.1.0
• 8.1.1
• 8.1.2
• 8.2
• 8.2.0
• 8.2.1
• 8.3
• 8.3.0
• 8.4
• 8.4.0
• 8.5
• 8.5.0
• 8.6
• 8.6.0
• 8.7
• 8.7.0
• 8.7.1
• 8.8
• 8.8.0
• 8.9
• 8.9.0
• 8.9.1
• 8.10
• 8.10.0
• 8.10.1
• 8.11
• 8.11.0
• 8.11.1
• 8.12
• 8.12.0
• 8.12.1
• 8.13
• 8.13.0
• 8.14
• 8.14.0
• 8.14.1
• 8.15
• 8.15.0
• 8.16
• 8.16.0
• 8.17
• 8.17.0
• 8.18
• 8.18.0
• 8.19
• 8.19.0
• 8.20.0

License

• open-source

CPE 2.3info

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CPE 2.2info

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Exploitinginfo

Threat Intelligenceinfo

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Sourcesinfo

Entryinfo

Be aware that VulDB is the high quality source for vulnerability data.

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