Authentication bypass in https://github.com/curl/curl
Priority MEDIUM 60CWE-305Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- High
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- Partial Red Hat: 5 fixed, 3 without a fix
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and Red Hat. Impact type from CWE-287.
Summary
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.
Why it matters now
Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.01803 78th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Partial Red Hat: 4 advisoriesRed Hat: 5 fixed, 3 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | https://github.com/curl/curl | Fixed in 8.0.0 | — | No fix listed | CNA |
- https://github.com/curl/curl Vendor— Affected Fixed in 8.0.0 Fixed in — No fix listed CNA
CPE configurations NVD · 15
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:haxx:libcurl:*:*:*:*:*:*:*:* | 7.13.0 – 7.88.1 | Vulnerable | Haxx |
| cpe:2.3:o:fedoraproject:fedora:36:*:*:*:*:*:*:* | 36 | Vulnerable | Fedoraproject |
| cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* | 10.0 | Vulnerable | Debian |
| cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:vmware_vsphere:*:* | not specified by NVD | Vulnerable | NetApp |
| cpe:2.3:a:netapp:ontap_9:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | NetApp |
| cpe:2.3:o:netapp:h300s_firmware:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | NetApp |
| cpe:2.3:h:netapp:h300s:-:*:*:*:*:*:*:* | not specified by NVD | Running on | NetApp |
| cpe:2.3:o:netapp:h500s_firmware:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | NetApp |
| cpe:2.3:h:netapp:h500s:-:*:*:*:*:*:*:* | not specified by NVD | Running on | NetApp |
| cpe:2.3:o:netapp:h700s_firmware:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | NetApp |
- cpe:2.3:a:haxx:libcurl:*:*:*:*:*:*:*:* Versions 7.13.0 – 7.88.1 Vulnerable ·Haxx
- cpe:2.3:o:fedoraproject:fedora:36:*:*:*:*:*:*:* Versions 36 Vulnerable ·Fedoraproject
- cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* Versions 10.0 Vulnerable ·Debian
- cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:vmware_vsphere:*:* Versions not specified by NVD Vulnerable ·NetApp
- cpe:2.3:a:netapp:ontap_9:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·NetApp
- cpe:2.3:o:netapp:h300s_firmware:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·NetApp
- cpe:2.3:h:netapp:h300s:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·NetApp
- cpe:2.3:o:netapp:h500s_firmware:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·NetApp
- cpe:2.3:h:netapp:h500s:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·NetApp
- cpe:2.3:o:netapp:h700s_firmware:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·NetApp
Show 5 more CPE
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:h:netapp:h700s:-:*:*:*:*:*:*:* | not specified by NVD | Running on | NetApp |
| cpe:2.3:o:netapp:h410s_firmware:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | NetApp |
| cpe:2.3:h:netapp:h410s:-:*:*:*:*:*:*:* | not specified by NVD | Running on | NetApp |
| cpe:2.3:a:splunk:universal_forwarder:*:*:*:*:*:*:*:* | 8.2.0 to before 8.2.12; 9.0.0 to before 9.0.6 | Vulnerable | Splunk |
| cpe:2.3:a:splunk:universal_forwarder:9.1.0:*:*:*:*:*:*:* | 9.1.0 | Vulnerable | Splunk |
- cpe:2.3:h:netapp:h700s:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·NetApp
- cpe:2.3:o:netapp:h410s_firmware:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·NetApp
- cpe:2.3:h:netapp:h410s:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·NetApp
- cpe:2.3:a:splunk:universal_forwarder:*:*:*:*:*:*:*:* Versions 8.2.0 to before 8.2.12; 9.0.0 to before 9.0.6 Vulnerable ·Splunk
- cpe:2.3:a:splunk:universal_forwarder:9.1.0:*:*:*:*:*:*:* Versions 9.1.0 Vulnerable ·Splunk
Remediation
Red Hat 4 advisories
- RHSA-2024:0428 Released 2024-01-25 · Red Hat rating Moderatecurl security and bug fix update
- Red Hat Enterprise Linux BaseOS EUS (v.8.6) curl-7.61.1-22.el8_6.12, libcurl-7.61.1-22.el8_6.12, libcurl-devel-7.61.1-22.el8_6.12 +1
- RHSA-2023:3355 Released 2023-06-05 · Red Hat rating ImportantRed Hat JBoss Core Services Apache HTTP Server 2.4.51 SP2 security update
- JBCS httpd 2.4.51.sp2
- RHSA-2023:3106 Released 2023-05-16 · Red Hat rating Moderatecurl security and bug fix update
- Red Hat Enterprise Linux BaseOS (v. 8) curl-7.61.1-30.el8_8.2, libcurl-7.61.1-30.el8_8.2, libcurl-devel-7.61.1-30.el8_8.2 +1
Show 1 more Red Hat advisories
- RHSA-2023:2650 Released 2023-05-09 · Red Hat rating Moderatecurl security update
- Red Hat Enterprise Linux AppStream (v. 9) libcurl-devel-7.76.1-23.el9_2.1
- Red Hat Enterprise Linux BaseOS (v. 9) curl-7.76.1-23.el9_2.1, curl-minimal-7.76.1-23.el9_2.1, libcurl-7.76.1-23.el9_2.1 +1
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Advisory ·
https://github.com/curl/curl — FEDORA-2023-7e7414e64d
4 records Highest priority Priority HIGH 2 HIGH, 2 MEDIUM
Other records, highest priority first
- TI-2023-12257 Injection in https://github.com/curl/curlPriority HIGH 82
- TI-2023-12258 Path traversal in https://github.com/curl/curlPriority HIGH 73
- TI-2023-12260 Authentication bypass in https://github.com/curl/curlPriority MEDIUM 60
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| .NET Core 3.1 on Red Hat Enterprise Linux | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 7 | Affected | No fix planned: Will not fix |
| JBCS httpd 2.4.51.sp2 | Fixed | RHSA-2023:3355 |
| Red Hat Enterprise Linux AppStream (v. 9) | Fixed | RHSA-2023:2650 |
| Red Hat Enterprise Linux BaseOS (v. 8) | Fixed | RHSA-2023:3106 |
| Red Hat Enterprise Linux BaseOS (v. 9) | Fixed | RHSA-2023:2650 |
| Red Hat Enterprise Linux BaseOS EUS (v.8.6) | Fixed | RHSA-2024:0428 |
Timeline
- 2026-10-02 Threatist record created from CVE-2023-27535
- 2026-10-03 Alias added: GHSA-q9fm-68jc-87x3
- 2026-10-09 Fix available: RHSA-2023:3355 · Red Hat
- 2026-10-16 Fix available: JBCS httpd 2.4.51.sp2 · Red Hat
References
Sources
- CVE-2023-27535 · CVE Program
- CVE-2023-27535 · NVD
- FIRST EPSS
- GHSA-q9fm-68jc-87x3 · GitHub Advisory Database · CC BY 4.0
- CVE-2023-27535 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences