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.
History

Wed, 27 Aug 2025 21:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'No', 'Exploitation': 'PoC', 'Technical Impact': 'Total'}, 'version': '2.0.3'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Thu, 13 Feb 2025 17:15:00 +0000

Type Values Removed Values Added
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. 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.

Thu, 17 Oct 2024 22:15:00 +0000

Type Values Removed Values Added
References
Metrics cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}

ssvc

{'options': {'Automatable': 'No', 'Exploitation': 'PoC', 'Technical Impact': 'Total'}, 'version': '2.0.3'}

cvssV3_1

{'score': 8.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: hackerone

Published:

Updated: 2025-08-27T20:32:53.710Z

Reserved: 2023-07-20T01:00:12.444Z

Link: CVE-2023-38545

cve-icon Vulnrichment

Updated: 2024-08-02T17:46:56.235Z

cve-icon NVD

Status : Modified

Published: 2023-10-18T04:15:11.077

Modified: 2025-02-13T17:16:47.823

Link: CVE-2023-38545

cve-icon Redhat

Severity : Important

Publid Date: 2023-10-11T00:00:00Z

Links: CVE-2023-38545 - Bugzilla

cve-icon OpenCVE Enrichment

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