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osvGoogleOSV:CURL-CVE-2023-38545
HistoryOct 11, 2023 - 8:00 a.m.

SOCKS5 heap buffer overflow

2023-10-1108:00:00
Google
osv.dev
5
buffer overflow
socks5 proxy
handshake
hostname
curl
software
bug

CVSS3

9.8

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

AI Score

9.7

Confidence

High

EPSS

0.003

Percentile

70.6%

This flaw makes curl overflow a heap based buffer in the SOCKS5 proxy
handshake.

When curl is asked to pass along the hostname to the SOCKS5 proxy to allow
that to resolve the address instead of it getting done by curl itself, the
maximum length that hostname can be is 255 bytes.

If the hostname is detected to be longer than 255 bytes, curl switches to
local name resolving and instead passes on the resolved address only to the
proxy. Due to a bug, the local variable that means β€œlet the host resolve the
name” could get the wrong value during a slow SOCKS5 handshake, and contrary
to the intention, copy the too long hostname to the target buffer instead of
copying just the resolved address there.

CVSS3

9.8

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

AI Score

9.7

Confidence

High

EPSS

0.003

Percentile

70.6%