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3.1

Processing sftp server read may cause null dereference

CVE-2023-3603 · published 3 years ago
Summary

A missing allocation check in sftp server processing read requests may cause a NULL dereference on low-memory conditions. The malicious client can request up to 4GB SFTP reads, causing allocation of up to 4GB buffers, which was not being checked for failure. This will likely crash the authenticated ...

What to do
  • Update libssh libssh to version 0.8.9 or later.
Affected software
VendorProductAffected versions
libssh libssh < 0.8.9
cpe:2.3:a:libssh:libssh:*:*:*:*:*:*:*:*
Original advisory text
Processing sftp server read may cause null dereference
A missing allocation check in sftp server processing read requests may cause a NULL dereference on low-memory conditions. The malicious client can request up to 4GB SFTP reads, causing allocation of up to 4GB buffers, which was not being checked for failure. This will likely crash the authenticated user's sftp server connection (if implemented as forking as recommended). For thread-based servers, this might also cause DoS for legitimate users.

Given this code is not in any released versions, no security releases have been issued.
References
Fix within
Internet-facing 60 days
Internal At next upgrade
  • Not known to be exploited
  • Needs hands-on effort to exploit
  • Gives an attacker partial control
Severity
3.1 Low
Exploitation
<1% chance of attack within 30 days
Type
CWE-476NULL Pointer Dereference
Timeline
Published21 Jul 2023
Updated3 Nov 2026
First seen29 Sep 2026
Sources
CVE-2023-3603 · NVD
CVE-2023-3603 · OSV
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