How severe is CVE-2021-25122?

CVE-2021-25122 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-25122?

CVE-2021-25122 affects the following packages: org.apache.tomcat.embed:tomcat-embed-core (Maven), org.apache.tomcat.embed:tomcat-embed-core (Maven), org.apache.tomcat.embed:tomcat-embed-core (Maven), org.apache.tomcat:tomcat-coyote (Maven). Ecosystems affected: Maven.

How do I fix CVE-2021-25122?

Update org.apache.tomcat.embed:tomcat-embed-core to 10.0.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-25122 is resolved across your whole dependency graph.

How do I detect CVE-2021-25122 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.tomcat.embed:tomcat-embed-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-25122 if there is no patch (or I can't update yet)?

Assume what was exposed is already known: rotate any credential, token or key that the affected component could return, restrict the endpoint to callers that genuinely need it, and strip sensitive fields from responses and error output at the boundary rather than relying on the client not to read them.

Is CVE-2021-25122 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-25122 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

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

CVE-2021-25122 has an EPSS (Exploit Prediction Scoring System) score of 18.1%, placing it in the 97th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score warrants monitoring and prompt remediation.

What type of vulnerability is CVE-2021-25122?

CVE-2021-25122 is classified as Information Exposure (CWE-200). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2021-25122 published, and has it been updated?

CVE-2021-25122 was published on March 1, 2021 and was last updated on August 27, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕

☕ Maven

Not in CISA KEV

HIGH severity

CVE-2021-25122 — tomcat-embed-core

HIGH

CVE-2021-25122 is a high-severity (CVSS 7.5) Information Exposure vulnerability in org.apache.tomcat.embed:tomcat-embed-core. EPSS puts its 30-day exploitation probability at 18.1% (97th percentile). A fix is available for org.apache.tomcat.embed:tomcat-embed-core — see the affected versions and patch details below.

Exposure of Sensitive Information to an Unauthorized Actor in Apache Tomcat

Also known asBIT-tomcat-2021-25122GHSA-j39c-c8hj-x4j3

Published

Mar 1, 2021

Updated

Aug 27, 2026

Affected

4 pkgs

Patched

4 / 4

Exploits

None indexed

Exploitation data as of Oct 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

18.1%probability of exploitation in next 30 days

Moderate Risk0.00%

Lower risk than most CVEs97th percentile — riskier than 97% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-25122 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,987 CVEs with a current EPSS score, this one falls in the 10–50% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

4 pkgs affected

☕org.apache.tomcat.embed:tomcat-embed-core☕org.apache.tomcat.embed:tomcat-embed-core☕org.apache.tomcat.embed:tomcat-embed-core☕org.apache.tomcat:tomcat-coyote

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

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.

Affected Packages

4 total 4 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.apache.tomcat.embed:tomcat-embed-core`	≥ 10.0.0-M1&&< 10.0.2	10.0.2`org.apache.tomcat.embed:tomcat-embed-core:10.0.2`
☕Maven	`org.apache.tomcat.embed:tomcat-embed-core`	≥ 9.0.0-M1&&< 9.0.43	9.0.43`org.apache.tomcat.embed:tomcat-embed-core:9.0.43`
☕Maven	`org.apache.tomcat.embed:tomcat-embed-core`	≥ 8.5.0&&< 8.5.63	8.5.63`org.apache.tomcat.embed:tomcat-embed-core:8.5.63`
☕Maven	`org.apache.tomcat:tomcat-coyote`	≥ 10.0.0-M1&&< 10.0.2	10.0.2`org.apache.tomcat:tomcat-coyote:10.0.2`

Affected Products

12 products · 55 configurations

Application

tomcatapache

≥ 9.0.0 && ≤ 9.0.41

2 versions

9.0.010.0.0

debian linuxdebian

2 versions

9.010.0

Application

agile product lifecycle managementoracle

2 versions

9.3.39.3.6

Application

communications cloud native core policyoracle

1 version

1.14.0

Application

communications cloud native core security edge protection proxyoracle

1 version

1.6.0

Application

communications instant messaging serveroracle

1 version

10.0.1.5.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.tomcat.embed:tomcat-embed-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.apache.tomcat.embed:tomcat-embed-core to 10.0.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-25122 is resolved across your whole dependency graph.
Workarounds
Assume what was exposed is already known: rotate any credential, token or key that the affected component could return, restrict the endpoint to callers that genuinely need it, and strip sensitive fields from responses and error output at the boundary rather than relying on the client not to read them.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

Red Hat Enterprise Linux 8's Identity Management and Certificate System are using a vulnerable version of Tomcat that is bundled into the `pki-servlet-engine` component. However, HTTP/2 is not enabled in such a configuration, and it is not possible to trigger the flaw in a supported setup. A future update may fix the…

Product	Fixed in	Advisory
Red Hat Fuse 7.11	`tomcat`	RHSA-2022:5532
Red Hat JBoss Web Server 5	`tomcat`	RHSA-2021:2562
Red Hat JBoss Web Server 5.5 on RHEL 7	`jws5-ecj-0:4.12.0-3.redhat_2.2.el7jws`	RHSA-2021:2561
Red Hat support for Spring Boot 2.3.10	`tomcat`	RHSA-2021:3425

UbuntuHIGH

USN-5360-1Ubuntu USN-6943-1Ubuntu

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2021-25122 in your dependencies?

Find it across Maven, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

7.5/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

None

Raw vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CWE Classification

CWE-200Information Exposure

Weaponization

No known public exploit tooling found.

OpenSSF Scorecard

Package health score

tomcat

5.9/10

Code-Review0/10

Maintained10/10

Branch-Protection3/10

Assessed Oct 5, 2026

Timeline

Disclosed

Mar 1, 2021

Last updated

Aug 27, 2026

Identifiers

CVE-2021-25122

GHSA-j39c-c8hj-x4j3

BIT-tomcat-2021-25122

Related vulnerabilities

This CVE is high severity; 7 of 8 other CVEs affecting tomcat-embed-core are rated as high or higher (top: critical).

CVE-2026-65905CVE-2026-65182CVE-2026-68525CVE-2026-43515CVE-2026-43513CVE-2026-43514CVE-2026-42498CVE-2026-41284

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedAug 27, 2026

CVE-2021-25122 — tomcat-embed-core

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

Description

Affected Packages

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

Fixing This On Your OS

Frequently Asked Questions

Is CVE-2021-25122 in your dependencies?