CVE-2021-42550 | RCE from attacker with configuration edit priviledges through JNDI lookup

Exp

In logback version 1.2.7 and prior versions, an attacker with the required privileges to edit configurations files could craft a malicious configuration allowing to execute arbitrary code loaded from LDAP servers.

Published: 2021-12-16 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-42550 is rated High Exploit Risk (71.5/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 2.73%). 3 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

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

Public exploit references (Exploit-DB) for CVE-2021-42550

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-42550

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 2026-03-06 2.60% 2.73% +0.12%
2 2026-03-04 4.29% 2.60% -1.69%
3 2026-03-01 — 4.29% —

Full EPSS history (43 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-42550

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.6 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H 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:H)
They need powerful rights—admin, root, or similar—before this pays off.
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:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 0.7 5.9 [email protected]
6.6 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H 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:H)
They need powerful rights—admin, root, or similar—before this pays off.
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:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 0.7 5.9 [email protected]
8.5 2.0 HIGH
AV:N/AC:M/Au:S/C:C/I:C/A:C 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:S)
A single authentication is required.
Confidentiality impact (C:C)
Complete confidentiality impact.
Integrity impact (I:C)
Complete integrity impact.
Availability impact (A:C)
Complete availability impact.
 6.8 10.0 [email protected]

Weakness enumeration for CVE-2021-42550

GitHub Security Advisory for CVE-2021-42550

GHSA-668q-qrv7-99fm · Severity: medium · Ecosystem: maven — Deserialization of Untrusted Data in logback

OS Trackers for CVE-2021-42550

vendor priority summary link
debian not yet assigned CVE-2021-42550 not yet assigned priority: Debian including 1 source packages (logback), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 4, open 1. https://security-tracker.debian.org/tracker/CVE-2021-42550
redhat medium — https://access.redhat.com/security/cve/CVE-2021-42550
ubuntu medium CVE-2021-42550 medium priority: Ubuntu including 1 source packages (logback), 14 status rows across 14 suites (bionic, focal, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, trusty, upstream, xenial): ignored 6, not-affected 4, released 4. https://ubuntu.com/security/CVE-2021-42550

Affected software / configurations for CVE-2021-42550

Vendor Product Version Raw CPE
qos logback <= 1.2.7 cpe:2.3:a:qos:logback:*:*:*:*:*:*:*:*
qos logback 1.3.0 cpe:2.3:a:qos:logback:1.3.0:alpha0:*:*:*:*:*:*
qos logback 1.3.0 cpe:2.3:a:qos:logback:1.3.0:alpha1:*:*:*:*:*:*
qos logback 1.3.0 cpe:2.3:a:qos:logback:1.3.0:alpha10:*:*:*:*:*:*
qos logback 1.3.0 cpe:2.3:a:qos:logback:1.3.0:alpha2:*:*:*:*:*:*
qos logback 1.3.0 cpe:2.3:a:qos:logback:1.3.0:alpha3:*:*:*:*:*:*
qos logback 1.3.0 cpe:2.3:a:qos:logback:1.3.0:alpha4:*:*:*:*:*:*
qos logback 1.3.0 cpe:2.3:a:qos:logback:1.3.0:alpha5:*:*:*:*:*:*
qos logback 1.3.0 cpe:2.3:a:qos:logback:1.3.0:alpha6:*:*:*:*:*:*
qos logback 1.3.0 cpe:2.3:a:qos:logback:1.3.0:alpha7:*:*:*:*:*:*
qos logback 1.3.0 cpe:2.3:a:qos:logback:1.3.0:alpha8:*:*:*:*:*:*
qos logback 1.3.0 cpe:2.3:a:qos:logback:1.3.0:alpha9:*:*:*:*:*:*
redhat satellite 6.0 cpe:2.3:a:redhat:satellite:6.0:*:*:*:*:*:*:*
netapp cloud_manager — cpe:2.3:a:netapp:cloud_manager:-:*:*:*:*:*:*:*
netapp service_level_manager — cpe:2.3:a:netapp:service_level_manager:-:*:*:*:*:*:*:*
netapp snap_creator_framework — cpe:2.3:a:netapp:snap_creator_framework:-:*:*:*:*:*:*:*
siemens sinec_nms < 1.0.3 cpe:2.3:a:siemens:sinec_nms:*:*:*:*:*:*:*:*

References for CVE-2021-42550

cvelogic Threat Intelligence