CVE-2023-27535
An authentication bypass vulnerability exists in libcurl <8.0.0 in the FTP connection reuse feature that can result in wrong credentials being used during subsequent transfers.
Published Mar 30, 2023 · corrected/updated Oct 14, 2026 · haxx libcurl · evidence confidence high
An authentication bypass vulnerability exists in libcurl <8.0.0 in the FTP connection reuse feature that can result in wrong credentials being used during subsequent transfers. Previously created connections are kept in a connection pool for reuse if they match the current setup. However, certain FTP settings such as CURLOPT_FTP_ACCOUNT, CURLOPT_FTP_ALTERNATIVE_TO_USER, CURLOPT_FTP_SSL_CCC, and CURLOPT_USE_SSL were not included in the configuration match checks, causing them to match too easily. This could lead to libcurl using the wrong credentials when performing a transfer, potentially allowing unauthorized access to sensitive information.
Grounded briefings
Catalog interpretations for three audiences. Each brief cites ingested metadata and the original advisories below. They are not independent research and they do not invent exploit steps.
Executive
CVE-2023-27535 is a medium public vulnerability record for haxx libcurl. It is not currently listed in the CISA Known Exploited catalog. Check the linked vendor or CERT advisories for patch status. This summary is a catalog interpretation of the ingested metadata and cites the original advisories below.
System administrator
Identify whether haxx libcurl is in your estate, then compare installed versions with the affected ranges. Affected packages or ranges on record: debian/debian linux (10.0); fedoraproject/fedora (36); haxx/libcurl; netapp/active iq unified manager. Check the linked vendor or CERT advisories for patch status. Prefer the vendor or distribution advisory linked in Sources before changing production systems. This is a catalog interpretation, not a runbook.
Security analyst
Signals on file: CVSS 5.9, EPSS 1.8%. It is not currently listed in the CISA Known Exploited catalog. Weakness classes: CWE-287, CWE-305. Sources contributing to this record: cve_org, epss, nvd. Public exploit references, when present, are outbound links only and are not proof of active exploitation. This is a catalog interpretation of stored metadata.
Exploitation and remediation
Exploitation evidence
Not listed as known exploited in CISA KEV. Not in the CISA KEV catalog.
Patch and remediation
No required-action text is stored yet. Use the vendor or CERT links in Sources for patch availability.
Safe detection guidance
Compare installed versions with the affected ranges below and verify the advisory from the original publisher. This site stores metadata and outbound links only; it does not ship exploit code or proof-of-concept payloads.
Code
The project this record applies to. Exploit listings stay in References.
No public source repository is identified for this product.
Timeline
Detection, updates, and resolution for this record.
Mar 30, 2023 · NIST NVD
Detected
An authentication bypass vulnerability exists in libcurl <8.0.0 in the FTP connection reuse feature that can result in wrong credentials being used during subsequent transfers. Previously created connections are kept in a connection pool for reuse if they match the current setup. However, certain FTP settings such as CURLOPT_FTP_ACCOUNT, CURLOPT_FTP_ALTERNATIVE_TO_USER, CURLOPT_FTP_SSL_CCC, and CU
Oct 14, 2026 · NIST NVD
Updated
An authentication bypass vulnerability exists in libcurl <8.0.0 in the FTP connection reuse feature that can result in wrong credentials being used during subsequent transfers. Previously created connections are kept in a connection pool for reuse if they match the current setup. However, certain FTP settings such as CURLOPT_FTP_ACCOUNT, CURLOPT_FTP_ALTERNATIVE_TO_USER, CURLOPT_FTP_SSL_CCC, and CU
Affected
- cpe debian/debian linux10.0
- cpe fedoraproject/fedora36
- cpe haxx/libcurlversion unspecified
- cpe netapp/active iq unified managerversion unspecified
- cpe netapp/h300s firmwareversion unspecified
- cpe netapp/h410s firmwareversion unspecified
- cpe netapp/h500s firmwareversion unspecified
- cpe netapp/h700s firmwareversion unspecified
- cpe netapp/ontap 9version unspecified
- cpe splunk/universal forwarderversion unspecified
Sources
- CVE.orgVulnerability recordCVE-2023-27535
Official CVE identifier
cve.org - FIRST EPSSExploitation probabilityCVE-2023-27535
30-day exploitation probability 1.8%
first.org - NIST NVDVulnerability recordCVE-2023-27535
An authentication bypass vulnerability exists in libcurl <8.0.0 in the FTP connection reuse feature that can result in wrong credentials being used during subsequent transfers. Previously created connections are kept in a connection pool for reuse if they match the current setup.
nvd.nist.gov