ZDF
Sign inSign up

Vulnerabilities

Vulnerability · CVE-2021-25122

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…

Published Mar 1, 2021 · catalog updated Oct 8, 2026 · Oracle

Check this week

CVE-2021-25122 is not in CISA KEV. FIRST estimates a 18.11% chance of exploitation in the next 30 days. Check whether you run Oracle.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
18.11%
Remediation
Advisory link
Affected products
cpe apache/tomcat

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe apache/tomcat9.0.0

How to fix CVE-2021-25122

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2021-25122 is not in CISA KEV. FIRST estimates a 18.11% chance of exploitation in the next 30 days. Check whether you run Oracle.

Which versions are affected?

Compare what you have installed with 9.0.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-200: Exposure of Sensitive Information. EPSS 18.11%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 1, 2021 · Oracle Critical Patch Updates

    Detected

    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.

  2. Oct 8, 2026 · Oracle Critical Patch Updates

    Updated

    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.

Sources

  • CVE.orgVulnerability recordCVE-2021-25122

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2021-25122

    30-day exploitation probability 18.1%

    first.org
  • Oracle Critical Patch UpdatesVendor advisoryCVE-2021-25122

    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.

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.