7.4

CVE-2026-9547: SSH improper host validation

Modified
AliasesALPINE-CVE-2026-9547UBUNTU-CVE-2026-9547DEBIAN-CVE-2026-9547
Published 03-07-2026Last modified 15-09-2026

Vulnerability summary

CVE-2026-9547 is a high (CVSS 7.4) vulnerability in curl. EPSS estimates a 0.36% chance of exploitation in the next 30 days, higher than 29.9% of scored vulnerabilities. 1 public exploit is recorded.

Priority
Prioritisepublic exploit

Public exploit (reference, Date unknown)

Source freshness unavailable

How is this decided?
CVSS score
7.4/10
010
High · v3.1 (CVE.org)
EPSS score
0.36%
0%100%
Low · -0.15 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits1reference

Advisory lineage

Upstream 0 · Downstream 15 · Related 12
OPENSUSE-SU-2026:11230-1OPENSUSE-SU-2026:21272-1RHSA-2026:29017RHSA-2026:34975RHSA-2026:55439RHSA-2026:55450

Timeline

  1. 03-07-2026
    PublishedVulnerability first disclosed.
  2. 15-09-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

7 scores · 7 sources · 1 version

EPSS trend

Probability

0.36%

Chance of exploitation in the next 30 days

Percentile

30%

Versus all other CVEs

30-day change

Decrease -0.15 pp

From 0.51% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

1 found
  • referenceUnverified

    Exploit Reference (hackerone.com)

    Maturity: unknown

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Chainguard11 products
  • eco-python-curl< 8.21.0-r0
  • eco-python-curl-minimal< 8.21.0-r0
  • eco-python-curl-minimal-bin< 8.21.0-r0
  • eco-python-curl-minimal-dev< 8.21.0-r0
  • eco-python-curl-minimal-doc< 8.21.0-r0
Alpine1 product
  • curl≥ 7.69.0, < 8.22.0-r0 | ≥ 7.69.0, < 8.21.0-r0
Curl1 product
  • curl≥ 7.69.0, < 8.14.2 | ≥ 8.15.0, < 8.16.1 | ≥ 8.17.0, < 8.20.1 | ≥ 507cf6a13db0375eadd4655b4c64710db29e9cf2, < 0b8dbbc63c98777e4584cb9fbd71df3464008ad1 | 8.20.0 | 8.19.0 | 8.18.0 | 8.17.0 | 8.16.0 | 8.15.0 | 8.14.1 | 8.14.0 | 8.13.0 | 8.12.1 | 8.12.0 | 8.11.1 | 8.11.0 | 8.10.1 | 8.10.0 | 8.9.1 | 8.9.0 | 8.8.0 | 8.7.1 | 8.7.0 | 8.6.0 | 8.5.0 | 8.4.0 | 8.3.0 | 8.2.1 | 8.2.0 | 8.1.2 | 8.1.1 | 8.1.0 | 8.0.1 | 8.0.0 | 7.88.1 | 7.88.0 | 7.87.0 | 7.86.0 | 7.85.0 | 7.84.0 | 7.83.1 | 7.83.0 | 7.82.0 | 7.81.0 | 7.80.0 | 7.79.1 | 7.79.0 | 7.78.0 | 7.77.0 | 7.76.1 | 7.76.0 | 7.75.0 | 7.74.0 | 7.73.0 | 7.72.0 | 7.71.1 | 7.71.0 | 7.70.0 | 7.69.1 | 7.69.0
Debian1 product
  • curlAll versions (No fix recorded) | < 8.21.0~rc2-1
Haxx1 product
  • curl≥ 7.69.0, < 8.21.0
Ubuntu1 product
  • curl< 7.81.0-1ubuntu1.25 | < 8.5.0-2ubuntu10.10 | < 8.14.1-2ubuntu1.4 | < 8.18.0-1ubuntu2.2
Wolfi1 product
  • libcurl4All versions (No fix recorded)

7 vendors · 17 products

References

11 links
Show all 11 references