CVE-2023-3603

Processing sftp server read may cause null dereference

MEDIUM
6.5
CVSS Score
Published: July 21, 2023 at 07:09 PM UTC
Updated: June 17, 2026 at 06:14 AM UTC
1 product affected across 1 vendorLibssh

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Severity
MEDIUM6.5
Exploit prediction
EPSS 0.9%
SSVC
No known exploit

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 0.8.9
Affected range stops below 0.8.9, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

References (2)

VDB Entryx_refsource_REDHATThird Party Advisory
https://access.redhat.com/security/cve/CVE-2023-3603
Issue Trackingx_refsource_REDHATThird Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2221791

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-476

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