$ cve CVE-2023-38545 JSON

CVE-2023-38545

9.8

CRITICAL · CVSS 3.1 · EPSS 78.5% (pctl 100)

Patch early

EPSS 78.5% — above the 10% action threshold.

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.

Scoring

CVSS	9.8 (CRITICAL, v3.1)
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS	78.48% — more likely to be exploited than 100% of all CVEs
Weakness	CWE-787
On CISA KEV	no
Public exploit	none known
Published	2023-10-18
Last modified	2026-06-17

Affected (13)

Vendor	Product
fedoraproject	fedora
haxx	libcurl
microsoft	windows 10 1809
microsoft	windows 10 21h2
microsoft	windows 10 22h2
microsoft	windows 11 21h2
microsoft	windows 11 22h2
microsoft	windows 11 23h2
microsoft	windows server 2019
microsoft	windows server 2022
netapp	active iq unified manager
netapp	oncommand insight
netapp	oncommand workflow automation

References

→ the Explorer · watch your stack · NVD