How severe is CVE-2023-3603?

CVE-2023-3603 has a CVSS 3.x base score of 3.1, rated low severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2023-3603 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-3603?

CVE-2023-3603 affects Libssh. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2023-3603?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2023-3603 published?

CVE-2023-3603 was published on 2023-07-21 and last updated on 2026-06-17.

CVE-2023-3603

CVE-2023-3603 is a low-severity vulnerability in Libssh with a CVSS 3.x base score of 3.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-476.

Key facts

Severity: Low (CVSS 3.x base score 3.1)
EPSS exploit prediction: 1% (51st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-476
Affected product: Libssh
Published: 2023-07-21
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2023-3603?: 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.
How severe is CVE-2023-3603?: CVE-2023-3603 has a CVSS 3.x base score of 3.1, rated low severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2023-3603 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-3603?: CVE-2023-3603 affects Libssh. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2023-3603?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2023-3603 published?: CVE-2023-3603 was published on 2023-07-21 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:libssh:libssh:*:*:*:*:*:*:*:*

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