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curl CVE-2026-9547

| EUVDEUVD-2026-41495 HIGH
7.4
CVSS 3.1 · Vendor
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Severity by source

Vendor (CNA) PRIMARY
7.4 HIGH
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
vuln.today AI
7.4 HIGH

Network MitM with no auth (AV:N/PR:N) but requires attacker positioning, a specific callback, and a prior key-type pin (AC:H); MitM enables read and modify of transfers (C:H/I:H), no availability impact (A:N).

3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
4.0 AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
SUSE
HIGH
qualitative
Red Hat
7.4 HIGH
qualitative

Primary rating from Vendor (CNA).

CVSS VectorVendor

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

Lifecycle Timeline

7
Analysis Updated
Jul 06, 2026 - 18:44 vuln.today
v5 (cvss_changed)
Analysis Updated
Jul 06, 2026 - 18:43 vuln.today
v4 (cvss_changed)
Analysis Updated
Jul 06, 2026 - 18:42 vuln.today
v3 (cvss_changed)
Analysis Updated
Jul 06, 2026 - 18:42 vuln.today
v2 (cvss_changed)
Re-analysis Queued
Jul 06, 2026 - 18:22 vuln.today
cvss_changed
CVSS changed
Jul 06, 2026 - 18:22 NVD
7.4 (HIGH)
Analysis Generated
Jun 24, 2026 - 18:30 vuln.today

Description PRE-NVD

Disclosed via oss-security. NVD scoring and full description are pending.

AnalysisAI

Host key verification bypass in libcurl affects applications using the CURLOPT_SSH_KEYFUNCTION callback for SCP:// or SFTP:// transfers, where a server presenting a host key of a different type than the one already recorded in known_hosts is silently accepted instead of rejected. This lets a network-positioned attacker impersonate a trusted SSH server and mount a man-in-the-middle attack, exposing and tampering with transferred data. There is no public exploit identified at time of analysis, and the EPSS probability is low (0.19%, 9th percentile), reflecting the specific application configuration and attacker positioning required.

Technical ContextAI

libcurl is the transfer engine underlying countless applications and utilities, and its SCP/SFTP support is provided through an SSH backend (typically libssh2 or libssh). Host authentication normally relies on matching the server's presented host key against a pinned entry in the known_hosts file. Applications can register the CURLOPT_SSH_KEYFUNCTION callback to programmatically decide whether to accept a host key. The flaw is a host-key verification weakness (functionally an improper certificate/key validation issue, CWE-295-class; no CWE was assigned in the source data): when the server offers a key of a different algorithm/type than the one already stored for that host, libcurl's callback path fails to treat the type mismatch as a rejection and permits the connection, defeating the trust-on-first-use pinning that known_hosts is meant to enforce.

RemediationAI

Patch available per vendor advisory (https://curl.se/docs/CVE-2026-9547.html); an exact fixed release version was not specified in the provided data, so upgrade to the latest curl/libcurl build offered by your vendor or distribution and confirm the fixed version against the advisory before deploying - for Debian/Ubuntu systems apply the packages referenced in USN-8487-1. Do not rely on an assumed version number; verify the fixed tag directly from curl.se. As a compensating control until patched, avoid or disable use of the CURLOPT_SSH_KEYFUNCTION callback so libcurl falls back to strict known_hosts matching, at the cost of losing the application's custom key-acceptance logic; alternatively, restrict SCP/SFTP transfers to hosts reached over trusted or authenticated network paths (VPN or mutually authenticated tunnels) to remove the man-in-the-middle opportunity, and pre-populate known_hosts with the correct key type for each server so that no legitimate type change is expected. Each mitigation reduces flexibility or requires tighter operational control of the network path.

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Vendor StatusVendor

SUSE

Severity: Important
Product Status
SLES15-SP5-CHOST-BYOS-SAP-CCloud Affected
SLES15-SP6-CHOST-BYOS Affected
SLES15-SP6-CHOST-BYOS-Aliyun Affected
SLES15-SP6-CHOST-BYOS-Azure Affected
SLES15-SP6-CHOST-BYOS-EC2 Affected

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CVE-2026-9547 vulnerability details – vuln.today

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