CVE-2023-6918 [Low] | Security Vulnerability in Libssh

A flaw was found in the libssh implements abstract layer for message digest (MD) operations implemented by different supported crypto backends. The return values from these were not properly checked, which could cause low-memory situations failures, NULL dereferences, crashes, or usage of the uninitialized memory as an input for the KDF. In this case, non-matching keys will result in decryption/integrity failures, terminating the connection.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.37%	1.42%	+1.05%
2	2026-03-01	0.31%	0.37%	+0.06%
3	2026-02-21	—	0.31%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.37%

1.42%

+1.05%

2026-03-01

0.31%

0.37%

+0.06%

2026-02-21

—

0.31%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
3.7	3.1	LOW	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:L) Might cause slowdowns, glitches, or partial disruption—not a full brick.	2.2	1.4	[email protected]
5.3	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. 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:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:L) Might cause slowdowns, glitches, or partial disruption—not a full brick.	3.9	1.4	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

3.7

3.1

LOW

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H): Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:L): Might cause slowdowns, glitches, or partial disruption—not a full brick.

2.2

1.4

[email protected]

5.3

3.1

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
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:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:L): Might cause slowdowns, glitches, or partial disruption—not a full brick.

3.9

1.4

[email protected]

OS Trackers for CVE-2023-6918

vendor	priority	summary	link
`alpine`	—	CVE-2023-6918: 1 source package rows (libssh); 13 state rows across 5 repos (3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 5, open 8.	https://security.alpinelinux.org/vuln/CVE-2023-6918
`debian`	not yet assigned	CVE-2023-6918 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-2023-6918
`redhat`	low	—	https://access.redhat.com/security/cve/CVE-2023-6918
`suse`	medium	CVE-2023-6918 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-2023-6918/
`ubuntu`	medium	CVE-2023-6918 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-2023-6918

Affected software / configurations for CVE-2023-6918

Vendor	Product	Version	Raw CPE
libssh	libssh	>= 0.9.0, < 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:::::::*
fedoraproject	fedora	39	cpe:2.3:o:fedoraproject:fedora:39:::::::*
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-2023-6918

URL	Tags
https://access.redhat.com/errata/RHSA-2024:2504
https://access.redhat.com/errata/RHSA-2024:3233
https://access.redhat.com/security/cve/CVE-2023-6918	Mailing List Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2254997	Issue Tracking Third Party Advisory
https://www.libssh.org/2023/12/18/libssh-0-10-6-and-libssh-0-9-8-security-releases/	Release Notes
https://www.libssh.org/security/advisories/CVE-2023-6918.txt	Vendor Advisory
https://lists.fedoraproject.org/archives/list/[email protected]/message/LZQVUHWVWRH73YBXUQJOD6CKHDQBU3DM/
https://lists.fedoraproject.org/archives/list/[email protected]/message/MKQRBF3DWMWPH36LBCOBUTSIZRTPEZXB/
https://security.netapp.com/advisory/ntap-20250214-0009/

URL

CVE-2023-6918 | Libssh: missing checks for return values for digests

Exploit prediction scoring system (EPSS) score for CVE-2023-6918

Common vulnerability scoring system (CVSS) metrics for CVE-2023-6918

Weakness enumeration for CVE-2023-6918

OS Trackers for CVE-2023-6918

Affected software / configurations for CVE-2023-6918

References for CVE-2023-6918