CVE-2023-38545

This flaw makes curl overflow a heap based buffer in the SOCKS5 proxy handshake. When curl is asked to pass along the host name to the SOCKS5 proxy to allow that to resolve the address instead of it getting done by curl itself, the maximum length that host name can be is 255 bytes. If the host name is detected to be longer, curl switches to local name resolving and instead passes on the resolved address only. Due to this bug, the local variable that means "let the host resolve the name" could get the wrong value during a slow SOCKS5 handshake, and contrary to the intention, copy the too long host name to the target buffer instead of copying just the resolved address there. The target buffer being a heap based buffer, and the host name coming from the URL that curl has been told to operate with.

Published: 2023-10-18 Last update: 2026-05-12 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-38545 is rated High Risk (72.4/100): CVSS Critical severity, with high exploitation likelihood (EPSS 26.25%, 96th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. High exploitation likelihood—assess exposure and prioritize remediation.

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

Exploit prediction scoring system (EPSS) score for CVE-2023-38545

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 2026-06-09 26.75% 26.25% -0.50%
2 2026-05-27 26.25% 26.75% +0.50%
3 2026-05-05 — 26.25% —

Full EPSS history (64 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-38545

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
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:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
8.8 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/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:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
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:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 5.9 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2023-38545

GitHub Security Advisory for CVE-2023-38545

GHSA-7xw9-w465-6x42 · Severity: critical — This flaw makes curl overflow a heap based buffer in the SOCKS5 proxy handshake. When curl is...

OS Trackers for CVE-2023-38545

vendor priority summary link
alpine — CVE-2023-38545: 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-2023-38545
debian not yet assigned CVE-2023-38545 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-2023-38545
gentoo high CVE-2023-38545: 1 GLSA(s) (202310-12), 1 atom(s) (net-misc/curl); latest impact high. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2023-38545
redhat high — https://access.redhat.com/security/cve/CVE-2023-38545
suse high CVE-2023-38545 severity important: SUSE including 335 source package names (1.2.3-2.2.19:libcurl4-8.0.1-150400.5.32.1, 1.2.3-3.2.19:libcurl4-8.0.1-150400.5.32.1, …), 780 product×package rows across 229 product lines (Container bci/bci-init, Container bci/golang, … (229 product lines)): Fixed 501, Known Affected 186, Known Not Affected 93. https://www.suse.com/security/cve/CVE-2023-38545/
ubuntu high CVE-2023-38545 high priority: Ubuntu including 1 source packages (curl), 9 status rows across 9 suites (bionic, focal, jammy, lunar, mantic, noble, trusty, upstream, xenial): not-affected 4, released 4, needs-triage 1. https://ubuntu.com/security/CVE-2023-38545

Affected software / configurations for CVE-2023-38545

Vendor Product Version Raw CPE
haxx libcurl >= 7.69.0, < 8.4.0 cpe:2.3:a:haxx:libcurl:*:*:*:*:*:*:*:*
fedoraproject fedora 37 cpe:2.3:o:fedoraproject:fedora:37:*:*:*:*:*:*:*
netapp active_iq_unified_manager — cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:vmware_vsphere:*:*
netapp active_iq_unified_manager — cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:windows:*:*
netapp oncommand_insight — cpe:2.3:a:netapp:oncommand_insight:-:*:*:*:*:*:*:*
netapp oncommand_workflow_automation — cpe:2.3:a:netapp:oncommand_workflow_automation:-:*:*:*:*:*:*:*
microsoft windows_10_1809 < 10.0.17763.5122 cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:*:*
microsoft windows_10_21h2 < 10.0.19044.3693 cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:*:*
microsoft windows_10_22h2 < 10.0.19045.3693 cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:*:*
microsoft windows_11_21h2 < 10.0.22000.2600 cpe:2.3:o:microsoft:windows_11_21h2:*:*:*:*:*:*:*:*
microsoft windows_11_22h2 < 10.0.22621.2715 cpe:2.3:o:microsoft:windows_11_22h2:*:*:*:*:*:*:*:*
microsoft windows_11_23h2 < 10.0.22631.2715 cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:*:*
microsoft windows_server_2019 < 10.0.17763.5122 cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*
microsoft windows_server_2022 < 10.0.20348.2113 cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*

References for CVE-2023-38545

URL Tags
http://seclists.org/fulldisclosure/2024/Jan/34 Mailing List Third Party Advisory
http://seclists.org/fulldisclosure/2024/Jan/37 Mailing List Third Party Advisory
http://seclists.org/fulldisclosure/2024/Jan/38 Mailing List Third Party Advisory
https://curl.se/docs/CVE-2023-38545.html Patch Third Party Advisory
https://forum.vmssoftware.com/viewtopic.php?f=8&t=8868
https://lists.fedoraproject.org/archives/list/[email protected]/message/OGMXNRNSJ4ETDK6FRNU3J7SABXPWCHSQ/ Mailing List Third Party Advisory
https://security.netapp.com/advisory/ntap-20231027-0009/ Third Party Advisory
https://security.netapp.com/advisory/ntap-20240201-0005/ Third Party Advisory
https://support.apple.com/kb/HT214036 Third Party Advisory
https://support.apple.com/kb/HT214057 Third Party Advisory
https://support.apple.com/kb/HT214058 Third Party Advisory
https://support.apple.com/kb/HT214063 Third Party Advisory
https://www.secpod.com/blog/high-severity-heap-buffer-overflow-vulnerability/ Patch Third Party Advisory
https://cert-portal.siemens.com/productcert/html/ssa-082556.html
https://cert-portal.siemens.com/productcert/html/ssa-093430.html
https://cert-portal.siemens.com/productcert/html/ssa-507364.html
https://cert-portal.siemens.com/productcert/html/ssa-832273.html
https://cert-portal.siemens.com/productcert/html/ssa-943925.html
https://github.com/UTsweetyfish/CVE-2023-38545
https://github.com/bcdannyboy/CVE-2023-38545
https://github.com/dbrugman/CVE-2023-38545-POC
cvelogic Threat Intelligence