CVE-2023-5871 | Libnbd: malicious nbd server may crash libnbd

A flaw was found in libnbd, due to a malicious Network Block Device (NBD), a protocol for accessing Block Devices such as hard disks over a Network. This issue may allow a malicious NBD server to cause a Denial of Service.

Published: 2023-11-27 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-5871 is rated Moderate Risk (41.5/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.92%). 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-2023-5871

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 0.04% 0.92% +0.89%
2 2026-03-08 0.10% 0.04% -0.06%
3 2025-11-21 — 0.10% —

Full EPSS history (11 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-5871

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
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]
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]

Weakness enumeration for CVE-2023-5871

OS Trackers for CVE-2023-5871

vendor priority summary link
alpine — CVE-2023-5871: 1 source package rows (libnbd); 2 state rows across 2 repos (3.22-community, edge-community); fixed 0, open 2. https://security.alpinelinux.org/vuln/CVE-2023-5871
debian unimportant CVE-2023-5871 unimportant priority: Debian including 1 source packages (libnbd), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2023-5871
redhat medium — https://access.redhat.com/security/cve/CVE-2023-5871
suse medium CVE-2023-5871 severity moderate: SUSE including 27 source package names (libnbd-1.18.1-150300.8.18.1, libnbd-1.18.1-2.1, …), 32 product×package rows across 6 product lines (SUSE Liberty Linux 9, SUSE Linux Enterprise Module for Server Applications 15 SP7, … (6 product lines)): Fixed 32. https://www.suse.com/security/cve/CVE-2023-5871/
ubuntu medium CVE-2023-5871 medium priority: Ubuntu including 1 source packages (libnbd), 12 status rows across 12 suites (bionic, focal, jammy, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): ignored 5, needs-triage 3, not-affected 3, released 1. https://ubuntu.com/security/CVE-2023-5871

Affected software / configurations for CVE-2023-5871

Vendor Product Version Raw CPE
redhat libnbd >= 1.17.4, < 1.18.2 cpe:2.3:a:redhat:libnbd:*:*:*:*:*:*:*:*
redhat libnbd 1.19.1 cpe:2.3:a:redhat:libnbd:1.19.1:*:*:*:*:*:*:*
redhat enterprise_linux 9.0 cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*

References for CVE-2023-5871

cvelogic Threat Intelligence