CVE & CISA-KEV Catalog

CVE-2026-9547

UNSCORED

Description

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.

How to fix

Remediation Available
curlDebian
Fixed in:8.21.0~rc2-1CVE-2026-9547
curlUbuntu
Fixed in:7.35.0-1ubuntu2.20+esm20USN-8487-1
Fixed in:7.47.0-1ubuntu2.19+esm16USN-8487-1
Fixed in:7.58.0-2ubuntu3.24+esm9USN-8487-1
Fixed in:7.68.0-1ubuntu2.25+esm4USN-8487-1
Fixed in:7.81.0-1ubuntu1.25USN-8487-1
Fixed in:8.5.0-2ubuntu10.10USN-8487-1
Fixed in:8.14.1-2ubuntu1.4USN-8487-1
libcurl3Ubuntu
Fixed in:7.35.0-1ubuntu2.20+esm20USN-8487-1
Fixed in:7.47.0-1ubuntu2.19+esm16USN-8487-1
libcurl3-gnutlsUbuntu
Fixed in:7.35.0-1ubuntu2.20+esm20USN-8487-1
Fixed in:7.47.0-1ubuntu2.19+esm16USN-8487-1
Fixed in:7.58.0-2ubuntu3.24+esm9USN-8487-1
Fixed in:7.68.0-1ubuntu2.25+esm4USN-8487-1
Fixed in:7.81.0-1ubuntu1.25USN-8487-1
libcurl3-nssUbuntu
Fixed in:7.35.0-1ubuntu2.20+esm20USN-8487-1
Fixed in:7.47.0-1ubuntu2.19+esm16USN-8487-1
Fixed in:7.58.0-2ubuntu3.24+esm9USN-8487-1
Fixed in:7.68.0-1ubuntu2.25+esm4USN-8487-1
Fixed in:7.81.0-1ubuntu1.25USN-8487-1
libcurl3t64-gnutlsUbuntu
Fixed in:8.5.0-2ubuntu10.10USN-8487-1
Fixed in:8.14.1-2ubuntu1.4USN-8487-1
libcurl4Ubuntu
Fixed in:7.58.0-2ubuntu3.24+esm9USN-8487-1
Fixed in:7.68.0-1ubuntu2.25+esm4USN-8487-1
Fixed in:7.81.0-1ubuntu1.25USN-8487-1
libcurl4-gnutls-devUbuntu
Fixed in:7.35.0-1ubuntu2.20+esm20USN-8487-1
Fixed in:7.47.0-1ubuntu2.19+esm16USN-8487-1
Fixed in:7.58.0-2ubuntu3.24+esm9USN-8487-1
Fixed in:7.68.0-1ubuntu2.25+esm4USN-8487-1
Fixed in:7.81.0-1ubuntu1.25USN-8487-1
Fixed in:8.5.0-2ubuntu10.10USN-8487-1
Fixed in:8.14.1-2ubuntu1.4USN-8487-1
libcurl4-nss-devUbuntu
Fixed in:7.35.0-1ubuntu2.20+esm20USN-8487-1
Fixed in:7.47.0-1ubuntu2.19+esm16USN-8487-1
Fixed in:7.58.0-2ubuntu3.24+esm9USN-8487-1
Fixed in:7.68.0-1ubuntu2.25+esm4USN-8487-1
Fixed in:7.81.0-1ubuntu1.25USN-8487-1
libcurl4-openssl-devUbuntu
Fixed in:7.35.0-1ubuntu2.20+esm20USN-8487-1
Fixed in:7.47.0-1ubuntu2.19+esm16USN-8487-1
Fixed in:7.58.0-2ubuntu3.24+esm9USN-8487-1
Fixed in:7.68.0-1ubuntu2.25+esm4USN-8487-1
Fixed in:7.81.0-1ubuntu1.25USN-8487-1
Fixed in:8.5.0-2ubuntu10.10USN-8487-1
Fixed in:8.14.1-2ubuntu1.4USN-8487-1
libcurl4t64Ubuntu
Fixed in:8.5.0-2ubuntu10.10USN-8487-1
Fixed in:8.14.1-2ubuntu1.4USN-8487-1

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3.1 Vector

No CVSS vector data available.

Exploit Intelligence

0.19%probability of exploitation in 30 days
9thpercentile

Low risk: more likely to be exploited than 9% of all known CVEs.

References

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Markdown

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HTML

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-03.