Description
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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| curl | curl | 8.4.0 – < 8.4.0 | 8.4.0 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | curl | 8.3.0-3 | — |
| Debian 13 | curl | 8.3.0-3 | — |
| Debian 12 | curl | 7.88.1-10+deb12u4 | DSA-5523-1 |
| Debian 11 | curl | 7.74.0-1.3+deb11u10 | DSA-5523-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 24.04 LTS | curl | 8.2.1-1ubuntu3.1 | — |
| Ubuntu 22.04 LTS | curl | 7.81.0-1ubuntu1.14 | USN-6429-1 |
| Ubuntu 20.04 LTS | curl | 7.68.0-1ubuntu2.20 | USN-6429-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 9 | curl +4 | 7.76.1-23.el9_2.4 | RHSA-2023:6745, RHSA-2023:5763 |
Show 5 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat Satellite Capsule 6 | mosquitto | 2.0.17-1.el8sat | RHSA-2024:0797 |
| Red Hat Satellite Capsule 6 | puppet-agent | 7.27.0-1.el8sat | RHSA-2024:0797 |
| Red Hat Satellite Capsule 6 | puppetserver | 7.14.0-1.el8sat | RHSA-2024:0797 |
| Red Hat Satellite 6 | candlepin +1 | 4.3.11-1.el8sat | RHSA-2024:0797 |
| Red Hat Satellite 6 | mosquitto | 2.0.17-1.el8sat | RHSA-2024:0797 |
| Red Hat Satellite 6 | puppet-agent | 7.27.0-1.el8sat | RHSA-2024:0797 |
| Red Hat Satellite 6 | puppetserver | 7.14.0-1.el8sat | RHSA-2024:0797 |
| Red Hat Satellite 6 | rubygem-grpc | 1.58.0-1.el8sat | RHSA-2024:0797 |
| Red Hat Satellite 6 | rubygem-puma | 6.3.1-1.el8sat | RHSA-2024:0797 |
| Red Hat Satellite 6 | rubygem-sidekiq | 6.5.12-1.el8sat | RHSA-2024:0797 |
| Red Hat Rhel Satellite Client 6 | puppet-agent | 7.27.0-1.el6sat | RHSA-2024:2011 |
| RHEL 9.0 EUS | curl +4 | 7.76.1-14.el9_0.9 | RHSA-2023:5700 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-curl +2 | 8.4.0-2.el7jbcs | RHSA-2023:7625 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_http2 | 1.15.19-32.el7jbcs | RHSA-2023:7625 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_jk +1 | 1.2.49-1.redhat_1.el7jbcs | RHSA-2023:7625 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-openssl +4 | 1:1.1.1k-16.el7jbcs | RHSA-2023:7625 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 9 | curl +4 | 7.76.1-23.el9_2.4 | ALSA-2023:6745, ALSA-2023:5763 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 9 | curl | 7.76.1-23.el9_2.4 | RLSA-2023:5763 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP5 | curl | 8.0.1-150400.5.32.1 | SUSE-SU-2023:4044-1 |
| SLES 15 SP4 | curl | 8.0.1-150400.5.32.1 | SUSE-SU-2023:4044-1 |
| SLES 12 SP5 | curl | 8.0.1-11.74.1 | SUSE-SU-2023:4043-1 |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 12 SP5 | curl | 8.0.1-11.74.1 | SUSE-SU-2023:4043-1 |
| SLE Micro 5.5 | curl | 8.0.1-150400.5.32.1 | SUSE-SU-2023:4044-1 |
| SLE Micro 5.4 | curl | 8.0.1-150400.5.32.1 | SUSE-SU-2023:4044-1 |
| SLE Micro 5.3 | curl | 8.0.1-150400.5.32.1 | SUSE-SU-2023:4044-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | cmake | 3.27.8-1.1 | openSUSE-SU-2024:13464-1 |
| openSUSE Tumbleweed | curl | 8.4.0-1.1 | openSUSE-SU-2024:13325-1 |
| openSUSE Leap 15.5 | curl | 8.0.1-150400.5.32.1 | SUSE-SU-2023:4044-1 |
| openSUSE Leap 15.4 | curl | 8.0.1-150400.5.32.1 | SUSE-SU-2023:4044-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | curl | 8.4.0-r0 | — |
| Alpine v3.23 | curl | 8.4.0-r0 | — |
| Alpine v3.22 | curl | 8.4.0-r0 | — |
| Alpine v3.21 | curl | 8.4.0-r0 | — |
| Alpine v3.20 | curl | 8.4.0-r0 | — |
Show 5 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | curl | 8.4.0-r0 | — |
| Alpine v3.18 | curl | 8.4.0-r0 | — |
| Alpine v3.17 | curl | 8.4.0-r0 | — |
| Alpine v3.16 | curl | 8.4.0-r0 | — |
| Alpine v3.15 | curl | 8.4.0-r0 | — |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | curl +4 | 8.3.0-1.amzn2023.0.2 | ALAS2023-2023-377 |
| Amazon Linux 2 | curl +2 | 8.3.0-1.amzn2.0.4 | ALAS2-2023-2287 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | cmake | 3.21.4-10 | — |
| Azure Linux 3 | tensorflow | 2.16.1-1 | — |
| Azure Linux 2 (CBL-Mariner) | cmake | 3.21.4-10 | — |
| Azure Linux 2 (CBL-Mariner) | curl | 8.3.0-2 | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 9 | curl +4 | 7.76.1-23.el9_2.4 | ELSA-2023-6745, ELSA-2023-5763 |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | curl +1 | 8.4.0-r0 | — |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.
GitHub 8 repositories
-
d0rb/CVE-2023-38545 ★ 21 · Oct 17, 2023
This script is designed to exploit a heap buffer overflow vulnerability in a socks5 proxy server.
-
UTsweetyfish/CVE-2023-38545 ★ 20 · Oct 11, 2023
Simple PoC causing overflow
-
imfht/CVE-2023-38545 ★ 8 · Oct 12, 2023
😄 CVE-2023-38545堆溢出的POC和分析文章
-
fatmo666/CVE-2023-38545-libcurl-SOCKS5-heap-buffer-overflow ★ 6 · Oct 12, 2023
Simple PoC causing overflow
-
bcdannyboy/CVE-2023-38545 ★ 4 · Oct 16, 2023
A proof of concept for testing CVE-2023-38545 against local curl
-
vanigori/CVE-2023-38545-sample ★ 3 · Oct 12, 2023
Dockerfile containing all the necessary setup files to demo the exploit
-
dbrugman/CVE-2023-38545-POC ★ 2 · Oct 16, 2023
CVE-2023-38545 POC for the curl command line tool
-
Yang-Shun-Yu/CVE-2023-38545 ★ 0 · Mar 19, 2024
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 48
- ALSA-2023:5763 Important: curl security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2023:6745 Important: curl security update AlmaLinux Security Advisories · Oct 29, 2026
- WID-SEC-2023-2570 cURL: Mehre Schwachstellen BSI CERT-Bund (WID) · Oct 28, 2026
- RHSA-2024:2011 Red Hat Security Advisory: Satellite Client Async Security Update Red Hat Security Advisories (RHSA) · Oct 15, 2026
- RHSA-2024:0797 Red Hat Security Advisory: Satellite 6.14.2 Async Security Update Red Hat Security Advisories (RHSA) · Oct 15, 2026
- RHSA-2023:7625 Red Hat Security Advisory: Red Hat JBoss Core Services Apache HTTP Server 2.4.57 SP2 security update Red Hat Security Advisories (RHSA) · Oct 15, 2026
- RHSA-2023:6745 Red Hat Security Advisory: curl security update Red Hat Security Advisories (RHSA) · Oct 15, 2026
- RHSA-2023:5763 Red Hat Security Advisory: curl security update Red Hat Security Advisories (RHSA) · Oct 15, 2026
- RHSA-2023:5700 Red Hat Security Advisory: curl security update Red Hat Security Advisories (RHSA) · Oct 15, 2026
- SSA-082556 SSA-082556: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP V3.1.5 Siemens ProductCERT · Oct 13, 2026
- ICSA-25-162-05 Siemens SIMATIC S7-1500 CPU family CISA ICS & IT advisories · May 14, 2026
- WID-SEC-2024-0123 Oracle Fusion Middleware: Mehrere Schwachstellen BSI CERT-Bund (WID) · May 7, 2026
- WID-SEC-2023-2690 Oracle MySQL: Mehrere Schwachstellen BSI CERT-Bund (WID) · May 5, 2026
- USN-6429-1 curl vulnerabilities Ubuntu Security Notices (USN) · Apr 27, 2026
- DSA-5523-1 curl - security update Debian Security (DSA / DLA) · Mar 9, 2026
- ICSA-26-043-04 Siemens Desigo CC Product Family and SENTRON Powermanager CISA ICS & IT advisories · Feb 12, 2026
- NCSC-2026-0051 Kwetsbaarheden verholpen in Siemens producten NCSC-NL (Netherlands) · Feb 10, 2026
- SSA-507364 SSA-507364: Heap Based Buffer Overflow Vulnerability in WIBU CodeMeter Runtime Affecting the Desigo CC Product Family and SENTRON Powermanager Siemens ProductCERT · Feb 10, 2026
- RLSA-2023:5763 Important: curl security update Rocky Linux Security Advisories · Feb 5, 2026
- openSUSE-SU-2024:13325-1 curl-8.4.0-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:13464-1 cmake-3.27.8-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2023:4044-1 Security update for curl SUSE / openSUSE Security Updates · Feb 4, 2026
- WID-SEC-2023-2788 GitLab: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jan 29, 2026
- ICSA-24-074-05 Siemens RUGGEDCOM APE1808 CISA ICS & IT advisories · Jan 14, 2026
- SSA-832273 SSA-832273: Multiple Vulnerabilities in Fortigate NGFW Before V7.4.3 on RUGGEDCOM APE1808 Devices Siemens ProductCERT · Jan 13, 2026
- WID-SEC-2024-3377 Dell PowerProtect Data Domain: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 12, 2025
- NCSC-2025-0187 Kwetsbaarheden verholpen in Siemens producten NCSC-NL (Netherlands) · Jun 10, 2025
- VDE-2024-073 Phoenix Contact: Multiple Vulnerabilities in PLCnext Firmware CERT@VDE · May 22, 2025
- SUSE-SU-2023:4043-1 Security update for curl SUSE / openSUSE Security Updates · May 2, 2025
- WID-SEC-2024-0119 Oracle MySQL: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 21, 2024
- NCSC-2024-0418 Kwetsbaarheden verholpen in Oracle Analytics NCSC-NL (Netherlands) · Oct 17, 2024
- ICSA-24-137-07 Siemens SIMATIC RTLS Locating Manager CISA ICS & IT advisories · Jun 11, 2024
- SSA-093430 SSA-093430: Multiple Vulnerabilities in SIMATIC RTLS Locating Manager before V3.0 Siemens ProductCERT · Jun 11, 2024
- WID-SEC-2024-0178 Apple iOS und iPadOS: Mehrere Schwachstellen BSI CERT-Bund (WID) · May 9, 2024
- WID-SEC-2024-0175 Apple macOS: Mehrere Schwachstellen BSI CERT-Bund (WID) · May 9, 2024
- WID-SEC-2024-0893 Oracle PeopleSoft: Mehrere Schwachstellen BSI CERT-Bund (WID) · Apr 16, 2024
- ICSA-24-046-15 Siemens SINEC NMS CISA ICS & IT advisories · Mar 12, 2024
- SSA-943925 SSA-943925: Multiple Vulnerabilities in SINEC NMS before V2.0 SP1 Siemens ProductCERT · Mar 12, 2024
- WID-SEC-2024-0290 HCL BigFix: Mehrere Schwachstellen BSI CERT-Bund (WID) · Feb 4, 2024
- VDE-2024-001 TRUMPF: Multiple products contain WIBU CodeMeter vulnerabilities CERT@VDE · Jan 29, 2024
- VDE-2024-007 WAGO: WIBU-SYSTEMS CodeMeter Runtime vulnerabilities in multiple products CERT@VDE · Jan 22, 2024
- WID-SEC-2024-0110 Oracle Database Server: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jan 16, 2024
- ICSA-24-004-01 Rockwell Automation FactoryTalk Activation CISA ICS & IT advisories · Jan 4, 2024
- VDE-2023-062 Phoenix Contact: WIBU-SYSTEMS CodeMeter Runtime vulnerabilities in multiple products CERT@VDE · Nov 21, 2023
- ELSA-2023-6745 Important: curl security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Nov 16, 2023
- ELSA-2023-5763 Important: curl security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Oct 18, 2023
- ALAS2-2023-2287 Important: curl security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Oct 11, 2023
- ALAS2023-2023-377 Important: curl security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Oct 11, 2023
References
- https://curl.se/docs/CVE-2023-38545.html
- https://security.netapp.com/advisory/ntap-20231027-0009/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/OGMXNRNSJ4ETDK6FRNU3J7SABXPWCHSQ/
- https://www.secpod.com/blog/high-severity-heap-buffer-overflow-vulnerability/
- https://support.apple.com/kb/HT214036
- https://support.apple.com/kb/HT214063
- https://support.apple.com/kb/HT214057
- https://support.apple.com/kb/HT214058
- http://seclists.org/fulldisclosure/2024/Jan/34
- http://seclists.org/fulldisclosure/2024/Jan/37
- http://seclists.org/fulldisclosure/2024/Jan/38
- https://security.netapp.com/advisory/ntap-20240201-0005/
- https://forum.vmssoftware.com/viewtopic.php?f=8&t=8868