CVE-2023-27537

Exp

A double free vulnerability exists in libcurl <8.0.0 when sharing HSTS data between separate "handles". This sharing was introduced without considerations for do this sharing across separate threads but there was no indication of this fact in the documentation. Due to missing mutexes or thread locks, two threads sharing the same HSTS data could end up doing a double-free or use-after-free.

Published: 2023-03-30 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-27537 is rated Exploit Available (50/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.08%). 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-2023-27537

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

Exploit prediction scoring system (EPSS) score for CVE-2023-27537

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 2026-04-12 0.05% 0.08% +0.03%
2 2026-03-04 0.06% 0.05% -0.01%
3 2026-03-01 — 0.06% —

Full EPSS history (16 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-27537

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:N/I:N/A:H 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:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.2 3.6 [email protected]

Weakness enumeration for CVE-2023-27537

OS Trackers for CVE-2023-27537

vendor priority summary link
alpine — CVE-2023-27537: 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-2023-27537
debian unimportant CVE-2023-27537 unimportant 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-2023-27537
gentoo high CVE-2023-27537: 1 GLSA(s) (202310-12), 1 atom(s) (net-misc/curl); latest impact high. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2023-27537
redhat low — https://access.redhat.com/security/cve/CVE-2023-27537
suse medium CVE-2023-27537 severity moderate: SUSE including 264 source package names (amazon/suse-sles-15-sp1-chost-byos-v20210304-hvm-ssd-x86_64, amazon/suse-sles-15-sp1-chost-byos-v20220127-hvm-ssd-x86_64, …), 365 product×package rows across 44 product lines (SUSE CaaS Platform 4.0, SUSE Enterprise Storage 7, … (44 product lines)): Known Affected 161, Known Not Affected 105, Fixed 99. https://www.suse.com/security/cve/CVE-2023-27537/
ubuntu low CVE-2023-27537 low priority: Ubuntu including 1 source packages (curl), 8 status rows across 8 suites (bionic, focal, jammy, kinetic, lunar, trusty, upstream, xenial): not-affected 6, pending 1, released 1. https://ubuntu.com/security/CVE-2023-27537

Affected software / configurations for CVE-2023-27537

Vendor Product Version Raw CPE
haxx libcurl 7.88.0 cpe:2.3:a:haxx:libcurl:7.88.0:*:*:*:*:*:*:*
haxx libcurl 7.88.1 cpe:2.3:a:haxx:libcurl:7.88.1:*:*:*:*:*:*:*
netapp active_iq_unified_manager — cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:vmware_vsphere:*:*
netapp clustered_data_ontap 9.0 cpe:2.3:a:netapp:clustered_data_ontap:9.0:-:*:*:*:*:*:*
broadcom brocade_fabric_operating_system_firmware — cpe:2.3:o:broadcom:brocade_fabric_operating_system_firmware:-:*:*:*:*:*:*:*
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-2023-27537

cvelogic Threat Intelligence