CVE-2021-40110 | Apache James IMAP vulnerable to a ReDoS

In Apache James, using Jazzer fuzzer, we identified that an IMAP user can craft IMAP LIST commands to orchestrate a Denial Of Service using a vulnerable Regular expression. This affected Apache James prior to 3.6.1 We recommend upgrading to Apache James 3.6.1 or higher , which enforce the use of RE2J regular expression engine to execute regex in linear time without back-tracking.

Published: 2022-01-04 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2021-40110 is rated Moderate Risk (61.9/100): CVSS High severity, with medium exploitation likelihood (EPSS 2.86%). Core evidence: EPSS rose +2.19% over the last day, indicating growing attacker interest. Mandatory action: 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-2021-40110

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 0.67% 2.86% +2.19%
2 2026-03-06 0.50% 0.67% +0.18%
3 2025-12-03 0.50%

Full EPSS history (16 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-40110

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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: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:H)
Could take the service down hard or make it unusable for people who depend on it.
3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
10.0 2.9 [email protected]

Weakness enumeration for CVE-2021-40110

GitHub Security Advisory for CVE-2021-40110

GHSA-r58x-wjg8-63m9 · Severity: high · Ecosystem: maven — Denial of Service in Apache James

Affected software / configurations for CVE-2021-40110

Vendor Product Version Raw CPE
apache james < 3.6.1 cpe:2.3:a:apache:james:*:*:*:*:*:*:*:*

References for CVE-2021-40110

URL Tags
http://www.openwall.com/lists/oss-security/2022/01/04/2 Mailing List Third Party Advisory
https://www.openwall.com/lists/oss-security/2022/01/04/2 Mailing List Third Party Advisory
cvelogic Threat Intelligence