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No exploitation reportedFix available

CVE-2023-3603

No exploitation reported by the sources we read.

  • Published2023-07-21
  • Fixed in0.8.9
  • WeaknessCWE-476

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2023-07-2120:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-11-03 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2023-3603?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2023-3603?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Libssh
BranchAffectedFixed in
0.8< 0.8.90.8.9

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA6 products

As redhat, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2024-01-23

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • libsshWolfiall versions · fixed in 0and 1 other package
  • libsshChainguardall versions · fixed in 0and 1 other package

Full record on NVD

Fix

  1. Update Libssh to 0.8.9

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub
Metasploit modules
none listed
Metasploit Framework

Sources

  • CISA-ADPSSVC decisionnone2024-09-26
  • OpenCVESSVC decisionnone—
  • CNACVSS 3.13.1known since 2026-10-23
  • NVDCVSS 3.16.5read 2026-10-23
  • CNAweakness (CWE)CWE-476known since 2026-10-23
  • NVDweakness (CWE)CWE-476read 2026-10-23
  • FIRST EPSSEPSS score0.9 %2026-11-03
  • OSVaffected packages—
  • GitHub Advisoriesadvisory—

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Published
2023-07-21
Last Modified
2026-06-17
NVD status
Modified
GitHub Advisory
GHSA-2c4f-vgwr-82q6

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.

Is CVE-2023-3603 actively exploited?

Active exploitation of CVE-2023-3603 has not been confirmed. Its EPSS score was 0.9% on 2026-11-03, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2023-3603?

CVE-2023-3603 has a CVSS v3 base score of 6.5 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

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