CVE-2023-27535

Exp

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.

Published: 2023-03-30 Last update: 2025-06-09 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-27535 is rated Exploit Available (50/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.04%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2023-27535

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2023-27535

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-19 0.07% 0.04% -0.04%
2 2025-11-21 0.27% 0.07% -0.19%
3 2025-11-18 — 0.27% —

Full EPSS history (17 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-27535

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 2.2 3.6 [email protected]
5.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 2.2 3.6 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2023-27535

OS Trackers for CVE-2023-27535

vendor priority summary link
alpine — CVE-2023-27535: 1 source package rows (curl); 7 state rows across 7 repos (3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 7, open 0. https://security.alpinelinux.org/vuln/CVE-2023-27535
debian not yet assigned CVE-2023-27535 not yet assigned priority: Debian including 1 source packages (curl), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2023-27535
gentoo high CVE-2023-27535: 1 GLSA(s) (202310-12), 1 atom(s) (net-misc/curl); latest impact high. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2023-27535
redhat medium — https://access.redhat.com/security/cve/CVE-2023-27535
suse medium CVE-2023-27535 severity moderate: SUSE including 410 source package names (0.23.0.3.2.423:libcurl4-7.66.0-150200.4.52.1, 0.58.0.1.217:libcurl4-7.79.1-150400.5.18.1, …), 929 product×package rows across 315 product lines (Container bci/bci-init, Container bci/dotnet-aspnet, … (315 product lines)): Fixed 778, Known Affected 142, Known Not Affected 9. https://www.suse.com/security/cve/CVE-2023-27535/
ubuntu medium CVE-2023-27535 medium priority: Ubuntu including 1 source packages (curl), 8 status rows across 8 suites (bionic, focal, jammy, kinetic, lunar, trusty, upstream, xenial): released 7, pending 1. https://ubuntu.com/security/CVE-2023-27535

Affected software / configurations for CVE-2023-27535

Vendor Product Version Raw CPE
haxx libcurl >= 7.13.0, <= 7.88.1 cpe:2.3:a:haxx:libcurl:*:*:*:*:*:*:*:*
fedoraproject fedora 36 cpe:2.3:o:fedoraproject:fedora:36:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
netapp active_iq_unified_manager — cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:vmware_vsphere:*:*
netapp ontap_9 — cpe:2.3:a:netapp:ontap_9:-:*:*:*:*:*:*:*
netapp h300s_firmware — cpe:2.3:o:netapp:h300s_firmware:-:*:*:*:*:*:*:*
netapp h500s_firmware — cpe:2.3:o:netapp:h500s_firmware:-:*:*:*:*:*:*:*
netapp h700s_firmware — cpe:2.3:o:netapp:h700s_firmware:-:*:*:*:*:*:*:*
netapp h410s_firmware — cpe:2.3:o:netapp:h410s_firmware:-:*:*:*:*:*:*:*
splunk universal_forwarder >= 8.2.0, < 8.2.12 cpe:2.3:a:splunk:universal_forwarder:*:*:*:*:*:*:*:*
splunk universal_forwarder >= 9.0.0, < 9.0.6 cpe:2.3:a:splunk:universal_forwarder:*:*:*:*:*:*:*:*
splunk universal_forwarder 9.1.0 cpe:2.3:a:splunk:universal_forwarder:9.1.0:*:*:*:*:*:*:*

References for CVE-2023-27535

cvelogic Threat Intelligence