proto-default skips SSH verification

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-12064
StatePUBLISHED
Assignercurl
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-03 07:16:24 UTC
Updated2026-07-07 19:43:11 UTC
DescriptionWhen 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.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS: 0.005740000 probability, percentile 0.432990000 (date 2026-07-09)

Problem Types: CWE-295 | CWE-297 Improper Validation of Certificate with Host Mismatch

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Haxx Curl All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Curl Curl affected 8.20.0 8.20.0 semver Not specified
CNA Curl Curl affected 8.19.0 8.19.0 semver Not specified
CNA Curl Curl affected 8.18.0 8.18.0 semver Not specified
CNA Curl Curl affected 8.17.0 8.17.0 semver Not specified
CNA Curl Curl affected 8.16.0 8.16.0 semver Not specified
CNA Curl Curl affected 8.15.0 8.15.0 semver Not specified
CNA Curl Curl affected 8.14.1 8.14.1 semver Not specified
CNA Curl Curl affected 8.14.0 8.14.0 semver Not specified
CNA Curl Curl affected 8.13.0 8.13.0 semver Not specified
CNA Curl Curl affected 8.12.1 8.12.1 semver Not specified
CNA Curl Curl affected 8.12.0 8.12.0 semver Not specified
CNA Curl Curl affected 8.11.1 8.11.1 semver Not specified
CNA Curl Curl affected 8.11.0 8.11.0 semver Not specified
CNA Curl Curl affected 8.10.1 8.10.1 semver Not specified
CNA Curl Curl affected 8.10.0 8.10.0 semver Not specified
CNA Curl Curl affected 8.9.1 8.9.1 semver Not specified
CNA Curl Curl affected 8.9.0 8.9.0 semver Not specified
CNA Curl Curl affected 8.8.0 8.8.0 semver Not specified
CNA Curl Curl affected 8.7.1 8.7.1 semver Not specified
CNA Curl Curl affected 8.7.0 8.7.0 semver Not specified
CNA Curl Curl affected 8.6.0 8.6.0 semver Not specified
CNA Curl Curl affected 8.5.0 8.5.0 semver Not specified
CNA Curl Curl affected 8.4.0 8.4.0 semver Not specified
CNA Curl Curl affected 8.3.0 8.3.0 semver Not specified
CNA Curl Curl affected 8.2.1 8.2.1 semver Not specified
CNA Curl Curl affected 8.2.0 8.2.0 semver Not specified
CNA Curl Curl affected 8.1.2 8.1.2 semver Not specified
CNA Curl Curl affected 8.1.1 8.1.1 semver Not specified
CNA Curl Curl affected 8.1.0 8.1.0 semver Not specified
CNA Curl Curl affected 8.0.1 8.0.1 semver Not specified
CNA Curl Curl affected 8.0.0 8.0.0 semver Not specified
CNA Curl Curl affected 7.88.1 7.88.1 semver Not specified
CNA Curl Curl affected 7.88.0 7.88.0 semver Not specified
CNA Curl Curl affected 7.87.0 7.87.0 semver Not specified
CNA Curl Curl affected 7.86.0 7.86.0 semver Not specified
CNA Curl Curl affected 7.85.0 7.85.0 semver Not specified
CNA Curl Curl affected 7.84.0 7.84.0 semver Not specified
CNA Curl Curl affected 7.83.1 7.83.1 semver Not specified
CNA Curl Curl affected 7.83.0 7.83.0 semver Not specified
CNA Curl Curl affected 7.82.0 7.82.0 semver Not specified
CNA Curl Curl affected 7.81.0 7.81.0 semver Not specified

References

ReferenceSourceLinkTags
hackerone.com/reports/3797526 134c704f-9b21-4f2e-91b3-4a467353bcc0 hackerone.com Exploit, Issue Tracking, Third Party Advisory
curl.se/docs/CVE-2026-12064.html 2499f714-1537-4658-8207-48ae4bb9eae9 curl.se Patch, Vendor Advisory
curl.se/docs/CVE-2026-12064.json 2499f714-1537-4658-8207-48ae4bb9eae9 curl.se Vendor Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: alienowo on hackerone (AntAISecurityLab) (en)

CNA: Daniel Stenberg (en)

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