No exploitation reportedFix available

CVE-2021-40110

Q: Is CVE-2021-40110 actively exploited?

Active exploitation of CVE-2021-40110 has not been confirmed. Its EPSS score was 2.9% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2021-40110?

CVE-2021-40110 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

No exploitation reported by the sources we read.

Published2022-01-04
Fixed in3.6.1

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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.

Timeline

dates in UTC

2022-01-0409:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-40110?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-40110?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV

Apache james

Branch	Affected	Fixed in	Source
3.6	< 3.6.1	3.6.1	NVD
3.x	≥ 3.1.0, < 3.6.1	3.6.1	OSV

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Apache james to 3.6.1

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.17.5read 2026-10-23
NVDCVSS 2.05read 2026-10-23
FIRST EPSSEPSS score2.9 %2026-10-23
OSVaffected packages—

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published: 2022-01-04
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-40110?

Is CVE-2021-40110 actively exploited?

Active exploitation of CVE-2021-40110 has not been confirmed. Its EPSS score was 2.9% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-40110?

CVE-2021-40110 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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