CVE-2023-27538
MEDIUMDescription
An authentication bypass vulnerability exists in libcurl prior to v8.0.0 where it reuses a previously established SSH connection despite the fact that an SSH option was modified, which should have prevented reuse. libcurl maintains a pool of previously used connections to reuse them for subsequent transfers if the configurations match. However, two SSH settings were omitted from the configuration check, allowing them to match easily, potentially leading to the reuse of an inappropriate connection.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Exploit Intelligence
Moderate risk: more likely to be exploited than 67% of all known CVEs.
References
Related Vulnerabilities
Other CWE-305 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2025-31161 | Critical | 9.8 | 100% | KEV + Ransom | Fix |
| CVE-2020-10923 | High | 8.8 | 85% | - | - |
| CVE-2023-28126 | Medium | 5.9 | 67% | - | - |
| CVE-2023-34124 | Critical | 9.8 | 46% | - | Fix |
| CVE-2025-32011 | Critical | 9.8 | 27% | - | - |
| CVE-2024-37085 | Medium | 6.8 | 26% | KEV + Ransom | Fix |
Common questions
How do I fix CVE-2023-27538?
Published advisories record a fix for 26 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2023-27538 being actively exploited?
Not that we know of. CVE-2023-27538 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 1.3% is the estimated probability that it will be exploited in the next 30 days. That is higher than 67% of all scored CVEs.
How severe is CVE-2023-27538?
CVE-2023-27538 has a CVSS v3 base score of 5.5, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2023-27538 affect?
Published advisories record a fix for curl (Debian), curl (Red Hat / RHEL), curl (Rocky), curl-debuginfo (Rocky), and 22 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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Markdown
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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 2025-06-09.