CVE-2026-9547
CVE-2026-9547 is a high-severity vulnerability in Haxx Curl with a CVSS 3.x base score of 7.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.
Key facts
- Severity: High (CVSS 3.x base score 7.4)
- EPSS exploit prediction: 0% (30th percentile)
- Actively exploited: Not listed in CISA KEV
- Affected product: Haxx Curl
- Published:
- Last modified:
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.
Frequently asked questions
- What is CVE-2026-9547?
- 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 severe is CVE-2026-9547?
- CVE-2026-9547 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
- Is CVE-2026-9547 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (30th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2026-9547?
- CVE-2026-9547 affects Haxx Curl. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2026-9547?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- When was CVE-2026-9547 published?
- CVE-2026-9547 was published on 2026-07-03 and last updated on 2026-07-07.
References
- https://curl.se/docs/CVE-2026-9547.html
- https://curl.se/docs/CVE-2026-9547.json
- https://hackerone.com/reports/3751712
Affected products (1)
- cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*
More vulnerabilities in Haxx Curl
- CVE-2026-9079 — Critical (CVSS 9.8): libcurl had a flaw that when instructed to clear proxy authentication credentials which made it not do so, leaving the…
- CVE-2026-8925 — Critical (CVSS 9.8): The curl logic that works with SASL authentication could end up cleaning up the GSASL context *twice* without clearing…
- CVE-2026-11856 — Critical (CVSS 9.8): Successfully using libcurl to do a transfer to a specific HTTP origin (`hostA`) with **Digest** authentication and then…
- CVE-2026-10536 — Critical (CVSS 9.8): A use-after-free vulnerability exists in libcurl when an application configures an HTTP/2 stream-dependency tree via…
- CVE-2022-32221 — Critical (CVSS 9.8): When doing HTTP(S) transfers, libcurl might erroneously use the read callback (`CURLOPT_READFUNCTION`) to ask for data…
- CVE-2022-32207 — Critical (CVSS 9.8): When curl < 7.84.0 saves cookies, alt-svc and hsts data to local files, it makes the operation atomic by finalizing the…