Threat Intelligence / CVE / CVE-2023-38545

CVE-2023-38545 — curl

CVSS v3.1 8.8 (HIGH) · EPSS 78.4% (higher than 99.5% of all scored CVEs) · Priority 10/10 · Published 2023-10-18

As of 2026-07-14, CVE-2023-38545 is a HIGH-severity vulnerability in curl, CVSS v3.1 8.8, EPSS 78.4% (99.5th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2023-38545, most recently “Multiple Fortinet FortiOS Vulnerabilities (incl. CVE-2024-23113) Affect Siemens RUGGEDCOM APE1808 via Bundled Fortinet NGFW < V7.4.3 (SSA-832273)”.

Last updated: 2026-07-14

What is 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.

The record classifies CVE-2023-38545 under weakness class CWE-787. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs a user to take an action first, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 1068 days ago.

Severity and exploitation probability

CVSS v3.1 base score
8.8 — HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS (FIRST)
78.4% probability of exploitation in the next 30 days, higher than 99.5% of all scored CVEs
CISA KEV
Not listed in the CISA Known Exploited Vulnerabilities catalog
Threadlinqs priority
10/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
Published
2023-10-18, last modified 2026-07-14

Is CVE-2023-38545 being exploited?

Weaponised exploit code for CVE-2023-38545 is publicly available. 9 public proof-of-concept repositories are tracked for this identifier.

Affected products and versions

How to fix CVE-2023-38545

The record marks a vendor fix as available for CVE-2023-38545. Patch reference: https://curl.se/docs/CVE-2023-38545.html. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.

Threat activity tracking CVE-2023-38545

1 tracked threat in the Threadlinqs corpus references CVE-2023-38545, either in the campaign’s CVE list or as an indicator on the campaign record.

Sources

Enriched from CVE.org, NVD, FIRST EPSS, GitHub Security Advisories, public proof-of-concept repositories. Last verified by Threadlinqs on . This product uses the NVD API but is not endorsed or certified by the NVD.

Other references

Showing 5 of 13 recorded references.

Full detection coverage & IOCs for threats exploiting CVE-2023-38545 are available via the Threadlinqs MCP server (Purple tier). View plans →

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