No exploitation reportedFix available

CVE-2021-25122

No exploitation reported by the sources we read.

Published2021-03-01
WeaknessCWE-200

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

When responding to new h2c connection requests, Apache Tomcat versions 10.0.0-M1 to 10.0.0, 9.0.0.M1 to 9.0.41 and 8.5.0 to 8.5.61 could duplicate request headers and a limited amount of request body from one request to another meaning user A and user B could both see the results of user A's request.

Timeline

dates in UTC

2021-03-0112:15CVE publishedNVD
2026-10-2319:23EPSS crossed 10 %FIRST EPSS

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 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-2021-25122?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-25122?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Apache Tomcat

Branch	Affected	Fixed in	Source
8.5	≥ 8.5.0, ≤ 8.5.61	no fix published	NVD
9.0	≥ 9.0.0, ≤ 9.0.41	no fix published	NVD
9.0	= 9.0.0	no fix published	NVD
10.0	= 10.0.0	no fix published	NVD

Oracle database

Branch	Affected	Fixed in	Source
12.2	= 12.2.0.1	no fix published	NVD
19.x	= 19c	no fix published	NVD
21.x	= 21c	no fix published	NVD

Oracle instantis enterprisetrack

Branch	Affected	Fixed in	Source
17.1	= 17.1	no fix published	NVD
17.2	= 17.2	no fix published	NVD
17.3	= 17.3	no fix published	NVD

9 more products in the sources.

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

Fix

Advisories and patches

Detection

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

Sources

CISA-ADPSSVC decisionnone2026-10-08
OpenCVESSVC decisionnone—
NVDCVSS 3.17.5read 2026-10-23
NVDCVSS 2.05read 2026-10-23
CNAweakness (CWE)CWE-200read 2026-10-23
NVDweakness (CWE)CWE-200read 2026-10-23
FIRST EPSSEPSS score18.1 %read 2026-10-23

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Published: 2021-03-01
Last Modified: 2026-10-08
NVD status: Modified

Frequently asked questions

What is CVE-2021-25122?

Is CVE-2021-25122 actively exploited?

Active exploitation of CVE-2021-25122 has not been confirmed. Its EPSS score was 18.1% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-25122?

CVE-2021-25122 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:H/I:N/A:N.

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