High 7.5Published Mar 1, 2021

CVE-2021-25122Apache Tomcat h2c request mix-up

Updated under an hour ago (Oct 28, 2026, 3:10 PM ET)

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It affects Apache Software Foundation Apache Tomcat and 12 other products. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for Apache Software Foundation Apache Tomcat

Exploited in the last 30 days

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.

CVSS: 7.5 HIGH (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Weakness (CWE): CWE-200
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: apache
NVD analysis: Modified
Record last updated: Oct 8, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Apache Software Foundation Apache Tomcat apache_software_foundation:apache_tomcat (from the name)	from Apache Tomcat 10 before 10.0.2; from Apache Tomcat 9 before 9.0.42; from Apache Tomcat 8.5 before 8.5.62	CNA record
apache tomcat apache:tomcat	from 8.5.0 through 8.5.61; from 9.0.0 through 9.0.41; 9.0.0; 9.0.0; 9.0.0; 9.0.0; 9.0.0; 9.0.0; and 28 more ranges	NVD
debian debian_linux debian:debian_linux	9.0; 10.0	NVD
oracle agile_product_lifecycle_management oracle:agile_product_lifecycle_management	9.3.3; 9.3.6	NVD
oracle communications_cloud_native_core_policy oracle:communications_cloud_native_core_policy	1.14.0	NVD
oracle communications_cloud_native_core_security_edge_protection_proxy oracle:communications_cloud_native_core_security_edge_protection_proxy	1.6.0	NVD
oracle communications_instant_messaging_server oracle:communications_instant_messaging_server	10.0.1.5.0	NVD
oracle database oracle:database	12.2.0.1; 19c; 21c	NVD
oracle graph_server_and_client oracle:graph_server_and_client	before 21.3.0; 21.3.0	NVD
oracle instantis_enterprisetrack oracle:instantis_enterprisetrack	17.1; 17.2; 17.3	NVD
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References

References

https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E	x-refsource-misc
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cusers.tomcat.apache.org%3E	mailing-list, x-refsource-mlist
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cdev.tomcat.apache.org%3E	mailing-list, x-refsource-mlist
https://lists.apache.org/thread.html/rf6d5d57b114678d8898005faef31e9fd6d7c981fcc4ccfc3bc272fc9%40%3Cdev.tomcat.apache.org%3E	mailing-list, x-refsource-mlist
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.apache.org%3E	mailing-list, x-refsource-mlist
http://www.openwall.com/lists/oss-security/2021/03/01/1	mailing-list, x-refsource-mlist
https://lists.apache.org/thread.html/rcd90bf36b1877e1310b87ecd14ed7bbb15da52b297efd9f0e7253a3b%40%3Cusers.tomcat.apache.org%3E	mailing-list, x-refsource-mlist
https://lists.apache.org/thread.html/rd0463f9a5cbc02a485404c4b990f0da452e5ac5c237808edba11c947%40%3Cusers.tomcat.apache.org%3E	mailing-list, x-refsource-mlist
https://lists.debian.org/debian-lts-announce/2021/03/msg00018.html	mailing-list, x-refsource-mlist
https://www.debian.org/security/2021/dsa-4891	vendor-advisory, x-refsource-debian
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The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.