# CVE-2026-9547: SSH improper host validation

> Attackers can bypass SSH host key validation in libcurl-based applications using SCP or SFTP, enabling man-in-the-middle attacks.

- **Severity:** High 7.4 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 3 Jul 2026
- **Updated:** 15 Sep 2026
- **Also known as:** ALPINE-CVE-2026-9547, BELL-CVE-2026-9547, CURL-CVE-2026-9547, DEBIAN-CVE-2026-9547, ECHO-07b2-9e60-e1ba, GHSA-xq9p-gxg6-f7q6, JLSEC-2026-1222, MINI-5jpx-2fcq-37cg, MINI-f3r3-3p4f-2rfh, ROOT-OS-ALPINE-315-CVE-2026-9547, ROOT-OS-ALPINE-320-CVE-2026-9547, ROOT-OS-ALPINE-321-CVE-2026-9547, ROOT-OS-ALPINE-322-CVE-2026-9547, ROOT-OS-DEBIAN-11-CVE-2026-9547, ROOT-OS-DEBIAN-12-CVE-2026-9547, ROOT-OS-DEBIAN-13-CVE-2026-9547, UBUNTU-CVE-2026-9547

## What is CVE-2026-9547?

CVE-2026-9547 is a high-severity vulnerability in Haxx Curl, published on 3 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-297 (Improper Validation of Certificate with Host Mismatch)

## Which versions are affected by CVE-2026-9547?

It affects 1 product.


Products: Haxx Curl.

## How do I fix CVE-2026-9547?

Upgrade to a fixed version.

## Is CVE-2026-9547 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-9547 exists.

## Other vulnerabilities in Haxx Curl

- [CVE-2026-19931](https://insights.sbomify.com/CVE-2026-19931/): Negotiate ambient user conn reuse (critical 9.8)
- [CVE-2026-10536](https://insights.sbomify.com/CVE-2026-10536/): HTTP/2 stream-dependency tree UAF (critical 9.8)
- [CVE-2026-11856](https://insights.sbomify.com/CVE-2026-11856/): cross-origin Digest auth state leak (critical 9.8)
- [CVE-2026-8925](https://insights.sbomify.com/CVE-2026-8925/): SASL double-free (critical 9.8)
- [CVE-2026-9079](https://insights.sbomify.com/CVE-2026-9079/): stale proxy password leak (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-9547 and fix it if it is affected.

What it is: CVE-2026-9547 is a high-severity vulnerability in Haxx Curl, published on 3 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-9547 exists.

Affected product: Haxx Curl. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-9547/ (Markdown: https://insights.sbomify.com/CVE-2026-9547/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-9547
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-9547
- OSV: https://osv.dev/vulnerability/CVE-2026-9547

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-9547/
Summaries are generated and may contain mistakes; the official description above is the record.