CVE-2023-6004 | Libssh: proxycommand/proxyjump features allow injection of malicious code through hostname

A flaw was found in libssh. By utilizing the ProxyCommand or ProxyJump feature, users can exploit unchecked hostname syntax on the client. This issue may allow an attacker to inject malicious code into the command of the features mentioned through the hostname parameter.

Published: 2024-01-03 Last update: 2025-11-04 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-6004 is rated Low Risk (32/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.45%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2023-6004

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.05% 0.45% +0.40%
2 2026-03-04 0.05% 0.05% +0.01%
3 2026-03-01 — 0.05% —

Full EPSS history (36 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-6004

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
4.8 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:L Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 1.3 3.4 [email protected]
4.8 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:L Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 1.3 3.4 [email protected]

Weakness enumeration for CVE-2023-6004

OS Trackers for CVE-2023-6004

vendor priority summary link
alpine — CVE-2023-6004: 1 source package rows (libssh); 5 state rows across 5 repos (3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 5, open 0. https://security.alpinelinux.org/vuln/CVE-2023-6004
debian not yet assigned CVE-2023-6004 not yet assigned priority: Debian including 1 source packages (libssh), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2023-6004
gentoo high CVE-2023-6004: 1 GLSA(s) (202312-16), 1 atom(s) (net-libs/libssh); latest impact high. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2023-6004
redhat low — https://access.redhat.com/security/cve/CVE-2023-6004
suse medium CVE-2023-6004 severity moderate: SUSE including 335 source package names (1.2.3-2.2.63:libssh-config-0.9.8-150400.3.3.1, 1.2.3-2.2.63:libssh4-0.9.8-150400.3.3.1, …), 896 product×package rows across 256 product lines (Container bci/golang, Container bci/nodejs, … (256 product lines)): Fixed 602, Known Affected 195, Known Not Affected 99. https://www.suse.com/security/cve/CVE-2023-6004/
ubuntu medium CVE-2023-6004 medium priority: Ubuntu including 1 source packages (libssh), 8 status rows across 8 suites (bionic, focal, jammy, lunar, mantic, trusty, upstream, xenial): released 7, ignored 1. https://ubuntu.com/security/CVE-2023-6004

Affected software / configurations for CVE-2023-6004

Vendor Product Version Raw CPE
libssh libssh >= 0.8.0, < 0.9.8 cpe:2.3:a:libssh:libssh:*:*:*:*:*:*:*:*
libssh libssh >= 0.10.0, < 0.10.6 cpe:2.3:a:libssh:libssh:*:*:*:*:*:*:*:*
fedoraproject fedora 38 cpe:2.3:o:fedoraproject:fedora:38:*:*:*:*:*:*:*
redhat enterprise_linux 8.0 cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
redhat enterprise_linux 9.0 cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*

References for CVE-2023-6004

cvelogic Threat Intelligence