CVE-2021-3731 | Improper Restriction of Rendered UI Layers or Frames in ledgersmb/ledgersmb

LedgerSMB does not sufficiently guard against being wrapped by other sites, making it vulnerable to 'clickjacking'. This allows an attacker to trick a targetted user to execute unintended actions.

Published: 2021-08-23 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-3731 is rated Low Risk (36.3/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.15%). 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-2021-3731

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 2025-12-13 0.28% 0.15% -0.13%
2 2025-03-30 0.55% 0.28% -0.27%
3 2025-03-29 — 0.55% —

Full EPSS history (11 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-3731

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:R/S:U/C:H/I:L/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: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:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 1.6 4.2 [email protected]
4.7 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/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: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:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 1.4 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:N/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2021-3731

OS Trackers for CVE-2021-3731

vendor priority summary link
debian not yet assigned CVE-2021-3731 not yet assigned priority: Debian including 1 source packages (ledgersmb), 2 status rows across 2 suites (bookworm, bullseye): resolved 2. https://security-tracker.debian.org/tracker/CVE-2021-3731
ubuntu medium CVE-2021-3731 medium priority: Ubuntu including 1 source packages (ledgersmb), 14 status rows across 14 suites (bionic, focal, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, trusty, upstream, xenial): released 5, ignored 4, not-affected 4, DNE 1. https://ubuntu.com/security/CVE-2021-3731

Affected software / configurations for CVE-2021-3731

Vendor Product Version Raw CPE
ledgersmb ledgersmb >= 1.1.0, <= 1.1.12 cpe:2.3:a:ledgersmb:ledgersmb:*:*:*:*:*:*:*:*
ledgersmb ledgersmb >= 1.2.0, <= 1.2.26 cpe:2.3:a:ledgersmb:ledgersmb:*:*:*:*:*:*:*:*
ledgersmb ledgersmb >= 1.3.0, <= 1.3.47 cpe:2.3:a:ledgersmb:ledgersmb:*:*:*:*:*:*:*:*
ledgersmb ledgersmb >= 1.4.0, <= 1.4.42 cpe:2.3:a:ledgersmb:ledgersmb:*:*:*:*:*:*:*:*
ledgersmb ledgersmb >= 1.5.0, <= 1.5.30 cpe:2.3:a:ledgersmb:ledgersmb:*:*:*:*:*:*:*:*
ledgersmb ledgersmb >= 1.6.0, <= 1.6.33 cpe:2.3:a:ledgersmb:ledgersmb:*:*:*:*:*:*:*:*
ledgersmb ledgersmb >= 1.7.0, <= 1.7.32 cpe:2.3:a:ledgersmb:ledgersmb:*:*:*:*:*:*:*:*
ledgersmb ledgersmb >= 1.8.0, <= 1.8.17 cpe:2.3:a:ledgersmb:ledgersmb:*:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
debian debian_linux 11.0 cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

References for CVE-2021-3731

cvelogic Threat Intelligence