CVE-2021-30640 | Auth weakness in JNDIRealm

A vulnerability in the JNDI Realm of Apache Tomcat allows an attacker to authenticate using variations of a valid user name and/or to bypass some of the protection provided by the LockOut Realm. This issue affects Apache Tomcat 10.0.0-M1 to 10.0.5; 9.0.0.M1 to 9.0.45; 8.5.0 to 8.5.65.

Published: 2021-07-12 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-30640 is rated Low Risk (36.9/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.12%). 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-2021-30640

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 2026-03-04 0.15% 0.12% -0.03%
2 2026-03-01 0.12% 0.15% +0.03%
3 2026-02-04 — 0.12% —

Full EPSS history (26 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-30640

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/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:L)
Some sensitive info could get out, but not a total data dump.
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 4.2 [email protected]
5.8 2.0 MEDIUM
AV:N/AC:M/Au:N/C:P/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:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 8.6 4.9 [email protected]

Weakness enumeration for CVE-2021-30640

GitHub Security Advisory for CVE-2021-30640

GHSA-36qh-35cm-5w2w · Severity: medium · Ecosystem: maven — Authentication Bypass by Alternate Name in Apache Tomcat

OS Trackers for CVE-2021-30640

vendor priority summary link
debian not yet assigned CVE-2021-30640 not yet assigned priority: Debian including 1 source packages (tomcat9), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-30640
gentoo low CVE-2021-30640: 1 GLSA(s) (202208-34), 1 atom(s) (www-servers/tomcat); latest impact low. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-30640
redhat low — https://access.redhat.com/security/cve/CVE-2021-30640
suse medium CVE-2021-30640 severity moderate: SUSE including 377 source package names (5.0.0-beta1.2.122:tomcat-9.0.36-13.1, 5.0.0-beta1.2.122:tomcat-el-3_0-api-9.0.36-13.1, …), 646 product×package rows across 59 product lines (Container containers/apache-tomcat, Container suse/manager/5.0/x86_64/server, … (59 product lines)): Fixed 394, Known Affected 231, Will Not Fix 21. https://www.suse.com/security/cve/CVE-2021-30640/
ubuntu medium CVE-2021-30640 medium priority: Ubuntu including 4 source packages (tomcat6, tomcat7, tomcat8, tomcat9), 64 status rows across 16 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 40, ignored 9, needed 7, not-affected 4, released 4. https://ubuntu.com/security/CVE-2021-30640

Affected software / configurations for CVE-2021-30640

Vendor Product Version Raw CPE
apache tomcat >= 7.0.0, < 7.0.109 cpe:2.3:a:apache:tomcat:*:*:*:*:*:*:*:*
apache tomcat >= 8.5.0, < 8.5.66 cpe:2.3:a:apache:tomcat:*:*:*:*:*:*:*:*
apache tomcat >= 9.0.0, < 9.0.46 cpe:2.3:a:apache:tomcat:*:*:*:*:*:*:*:*
apache tomcat >= 10.0.0, < 10.0.6 cpe:2.3:a:apache:tomcat:*:*:*:*:*:*:*:*
oracle communications_cloud_native_core_policy 1.14.0 cpe:2.3:a:oracle:communications_cloud_native_core_policy:1.14.0:*:*:*:*:*:*:*
oracle communications_diameter_signaling_router >= 8.0.0, <= 8.5.0 cpe:2.3:a:oracle:communications_diameter_signaling_router:*:*:*:*:*:*:*:*
oracle communications_pricing_design_center 12.0.0.3.0 cpe:2.3:a:oracle:communications_pricing_design_center:12.0.0.3.0:*:*:*:*:*:*:*
oracle hospitality_cruise_shipboard_property_management_system 20.1.0 cpe:2.3:a:oracle:hospitality_cruise_shipboard_property_management_system:20.1.0:*:*:*:*:*:*:*
oracle tekelec_platform_distribution >= 7.4.0, <= 7.7.1 cpe:2.3:a:oracle:tekelec_platform_distribution:*:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
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-2021-30640

cvelogic Threat Intelligence