CVE-2023-38545

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2023-10-18. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Weaponized
9.8
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • High exploitation likelihood — EPSS 78%
CISA-KEV: Not listedEPSS: 78%CVSS: 9.8Exploit: NoneExposed: 0

A fix is available — apply it.

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.

CVSS v3
9.8
EG Score
9.8(medium)
EPSS
99.5%
KEV
Not listed

Published

October 18, 2023

Last Modified

May 12, 2026

Advisory Details (9)

Auto-updated May 12, 2026
No patch confirmed yet.
generic

About the security content of macOS Monterey 12.7.3 - Apple Support

https://support.apple.com/kb/HT214057
generic

About the security content of macOS Sonoma 14.2 - Apple Support

https://support.apple.com/kb/HT214036
generic

NetApp Product Security

https://security.netapp.com/advisory/ntap-20240201-0005/
generic

NetApp Product Security

https://security.netapp.com/advisory/ntap-20231027-0009/
generic

[SECURITY] Fedora 37 Update: curl-7.85.0-12.fc37 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/[email protected]/message/OGMXNRNSJ4ETDK6FRNU3J7SABXPWCHSQ/
generic

curl - SOCKS5 heap buffer overflow - CVE-2023-38545

https://curl.se/docs/CVE-2023-38545.html
generic

Full Disclosure: APPLE-SA-01-22-2024-7 macOS Monterey 12.7.3

http://seclists.org/fulldisclosure/2024/Jan/38
generic

Full Disclosure: APPLE-SA-01-22-2024-6 macOS Ventura 13.6.4

http://seclists.org/fulldisclosure/2024/Jan/37
generic

Full Disclosure: APPLE-SA-01-22-2024-3 iOS 16.7.5 and iPadOS 16.7.5

http://seclists.org/fulldisclosure/2024/Jan/34

Vendor Advisories for CVE-2023-38545(3)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(9)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulibcurl4-openssl-dev (7.88.1-8ubuntu2.3) @ lunar2026-05-20ubuntu
ubuntulibcurl4-openssl-dev (8.2.1-1ubuntu3.1) @ mantic2026-05-20ubuntu
redhatpuppet-agent-0:7.27.0-1.el9sat2024-04-23redhat
redhatpuppet-agent-0:7.27.0-1.el8sat2024-02-13redhat
redhatjbcs-httpd24-curl2023-12-07redhat
redhatjbcs-httpd24-curl-0:8.4.0-2.el7jbcs2023-12-07redhat
redhatcurl-0:7.76.1-26.el9_3.22023-11-07redhat
redhatcurl-0:7.76.1-23.el9_2.42023-10-17redhat
redhatcurl-0:7.76.1-14.el9_0.92023-10-13redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(8)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 3× in last 7d / 30× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 107 total refreshes for this CVE.

  1. 2026-07-02 16:59 UTCEPSS rescore
  2. 2026-06-30 23:21 UTCEPSS rescore
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  16. 2026-06-19 16:55 UTCOSV refresh
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  1. 2026-06-11 13:59 UTCEPSS rescore
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  22. 2026-05-30 22:53 UTCOSV refresh
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  51. 2026-05-20 09:04 UTCEG score recompute
  52. 2026-05-20 09:04 UTCVendor advisory
  53. 2026-05-20 09:04 UTCGHSA enrichment
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  55. 2026-05-20 04:59 UTCVendor advisory
  56. 2026-05-20 04:59 UTCGHSA enrichment
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  58. 2026-05-20 00:54 UTCVendor advisory
  59. 2026-05-20 00:54 UTCGHSA enrichment
  60. 2026-05-19 20:48 UTCEG score recompute
  61. 2026-05-19 20:48 UTCVendor advisory
  62. 2026-05-19 20:48 UTCGHSA enrichment
  63. 2026-05-19 16:43 UTCEG score recompute
  64. 2026-05-19 16:43 UTCVendor advisory
  65. 2026-05-19 16:43 UTCGHSA enrichment
  66. 2026-05-19 12:38 UTCEG score recompute
  67. 2026-05-19 12:38 UTCVendor advisory
  68. 2026-05-19 12:38 UTCGHSA enrichment
  69. 2026-05-19 08:33 UTCEG score recompute
  70. 2026-05-19 08:33 UTCVendor advisory
  71. 2026-05-19 08:33 UTCGHSA enrichment
  72. 2026-05-19 04:28 UTCEG score recompute
  73. 2026-05-19 04:28 UTCVendor advisory
  74. 2026-05-19 04:28 UTCGHSA enrichment
  75. 2026-05-19 00:24 UTCEG score recompute

Publicly available exploits

(7 references)

Working exploit code is in the public domain (7 GitHub PoCs). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCd0rb/CVE-2023-38545
    First seen Oct 17, 2023

    This script is designed to exploit a heap buffer overflow vulnerability in a socks5 proxy server.

    Open source ↗
  • GitHub PoCdbrugman/CVE-2023-38545-POC
    First seen Oct 16, 2023

    CVE-2023-38545 POC for the curl command line tool

    Open source ↗
  • GitHub PoCbcdannyboy/CVE-2023-38545
    First seen Oct 16, 2023

    A proof of concept for testing CVE-2023-38545 against local curl

    Open source ↗
  • GitHub PoCfatmo666/CVE-2023-38545-libcurl-SOCKS5-heap-buffer-overflow
    First seen Oct 12, 2023

    Simple PoC causing overflow

    Open source ↗
  • GitHub PoCimfht/CVE-2023-38545
    First seen Oct 12, 2023

    😄 CVE-2023-38545堆溢出的POC和分析文章

    Open source ↗
  • GitHub PoCvanigori/CVE-2023-38545-sample
    First seen Oct 12, 2023

    Dockerfile containing all the necessary setup files to demo the exploit

    Open source ↗
  • GitHub PoCUTsweetyfish/CVE-2023-38545
    First seen Oct 11, 2023

    Simple PoC causing overflow

    Open source ↗

Frequently asked(5)

What is CVE-2023-38545?
CVE-2023-38545 is a critical vulnerability published on October 18, 2023. 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…
When was CVE-2023-38545 disclosed?
CVE-2023-38545 was first published in the National Vulnerability Database on October 18, 2023, with the most recent update on May 12, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2023-38545 actively exploited?
CVE-2023-38545 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 99.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2023-38545?
CVE-2023-38545 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2023-38545?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2023-38545, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2023-38545

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