CVE-2023-3347 | Samba: smb2 packet signing is not enforced when "server signing = required" is set

A vulnerability was found in Samba's SMB2 packet signing mechanism. The SMB2 packet signing is not enforced if an admin configured "server signing = required" or for SMB2 connections to Domain Controllers where SMB2 packet signing is mandatory. This flaw allows an attacker to perform attacks, such as a man-in-the-middle attack, by intercepting the network traffic and modifying the SMB2 messages between client and server, affecting the integrity of the data.

Published: 2023-07-20 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-3347 is rated Moderate Risk (44.5/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.42%). Review affected assets and schedule remediation.

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-2023-3347

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 2025-11-21 0.90% 0.42% -0.48%
2 2025-11-18 0.42% 0.90% +0.48%
3 2025-04-15 — 0.42% —

Full EPSS history (8 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-3347

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N 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:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 2.2 3.6 [email protected]
5.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N 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:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 2.2 3.6 [email protected]

Weakness enumeration for CVE-2023-3347

OS Trackers for CVE-2023-3347

vendor priority summary link
alpine — CVE-2023-3347: 1 source package rows (samba); 20 state rows across 5 repos (3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 0, open 20. https://security.alpinelinux.org/vuln/CVE-2023-3347
debian unimportant CVE-2023-3347 unimportant priority: Debian including 1 source packages (samba), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2023-3347
gentoo high CVE-2023-3347: 1 GLSA(s) (202402-28), 1 atom(s) (net-fs/samba); latest impact high. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2023-3347
redhat medium — https://access.redhat.com/security/cve/CVE-2023-3347
suse medium CVE-2023-3347 severity moderate: SUSE including 517 source package names (amazon/suse-sles-15-sp1-chost-byos-v20210304-hvm-ssd-x86_64, amazon/suse-sles-15-sp1-chost-byos-v20220127-hvm-ssd-x86_64, …), 1761 product×package rows across 92 product lines (Image SLES15-SP5-Azure-3P, Image SLES15-SP5-Azure-Basic, … (92 product lines)): Known Not Affected 1245, Fixed 285, Known Affected 231. https://www.suse.com/security/cve/CVE-2023-3347/
ubuntu medium CVE-2023-3347 medium priority: Ubuntu including 1 source packages (samba), 8 status rows across 8 suites (bionic, focal, jammy, kinetic, lunar, trusty, upstream, xenial): not-affected 6, needs-triage 1, released 1. https://ubuntu.com/security/CVE-2023-3347

Affected software / configurations for CVE-2023-3347

Vendor Product Version Raw CPE
samba samba >= 4.17.0, < 4.17.10 cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:*
samba samba >= 4.18.0, < 4.18.5 cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:*
redhat storage 3.0 cpe:2.3:a:redhat:storage:3.0:*:*:*:*:*:*:*
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:*:*:*:*:*:*:*
fedoraproject fedora 38 cpe:2.3:o:fedoraproject:fedora:38:*:*:*:*:*:*:*

References for CVE-2023-3347

cvelogic Threat Intelligence