CVE-2021-25122

7.5 high SSVC exploitation: none Modified

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.

Fix

Patch, vendor advisory and mitigation references on NVD 22

https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://www.oracle.com//security-alerts/cpujul2021.html Patch, Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.html Patch, Third Party Advisory
https://www.oracle.com/security-alerts/cpuoct2021.html Patch, Third Party Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://www.oracle.com//security-alerts/cpujul2021.html Patch, Third Party Advisory

Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.

Change history 1

2026-10-15 00:45First seenCVSS 7.5 · apache, debian, oracleNVD modified 2026-10-08 22:17

Affected (CPE criteria) 54

cpe:2.3:a:apache:tomcat:*:*:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:9.0.0:milestone1:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:9.0.0:milestone10:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:9.0.0:milestone11:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:9.0.0:milestone12:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:9.0.0:milestone13:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:9.0.0:milestone14:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:9.0.0:milestone15:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:9.0.0:milestone16:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:9.0.0:milestone17:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:9.0.0:milestone18:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:9.0.0:milestone19:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:9.0.0:milestone2:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:9.0.0:milestone20:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:9.0.0:milestone21:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:9.0.0:milestone22:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:9.0.0:milestone23:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:9.0.0:milestone24:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:9.0.0:milestone25:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:9.0.0:milestone26:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:9.0.0:milestone27:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:9.0.0:milestone3:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:9.0.0:milestone4:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:9.0.0:milestone5:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:10.0.0:-:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:10.0.0:milestone1:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:10.0.0:milestone10:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:10.0.0:milestone2:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:10.0.0:milestone3:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:10.0.0:milestone4:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:10.0.0:milestone5:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:10.0.0:milestone6:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:10.0.0:milestone7:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:10.0.0:milestone8:*:*:*:*:*:*
cpe:2.3:a:apache:tomcat:10.0.0:milestone9:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
cpe:2.3:a:oracle:agile_product_lifecycle_management:9.3.3:*:*:*:*:*:*:*
cpe:2.3:a:oracle:agile_product_lifecycle_management:9.3.6:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_cloud_native_core_policy:1.14.0:*:*:*:*:*:*:*
and 14 more

References 44

http://www.openwall.com/lists/oss-security/2021/03/01/1 Mailing List, Third Party Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.apache.org%3E
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cdev.tomcat.apache.org%3E
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cusers.tomcat.apache.org%3E
https://lists.apache.org/thread.html/rcd90bf36b1877e1310b87ecd14ed7bbb15da52b297efd9f0e7253a3b%40%3Cusers.tomcat.apache.org%3E
https://lists.apache.org/thread.html/rd0463f9a5cbc02a485404c4b990f0da452e5ac5c237808edba11c947%40%3Cusers.tomcat.apache.org%3E
https://lists.apache.org/thread.html/rf6d5d57b114678d8898005faef31e9fd6d7c981fcc4ccfc3bc272fc9%40%3Cdev.tomcat.apache.org%3E
https://lists.debian.org/debian-lts-announce/2021/03/msg00018.html Mailing List, Third Party Advisory
https://security.gentoo.org/glsa/202208-34 Third Party Advisory
https://security.netapp.com/advisory/ntap-20210409-0002/ Third Party Advisory
https://www.debian.org/security/2021/dsa-4891 Third Party Advisory
https://www.oracle.com//security-alerts/cpujul2021.html Patch, Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.html Patch, Third Party Advisory
https://www.oracle.com/security-alerts/cpuoct2021.html Patch, Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/03/01/1 Mailing List, Third Party Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.apache.org%3E
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cannounce.tomcat.apache.org%3E Mailing List, Vendor Advisory
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cdev.tomcat.apache.org%3E
https://lists.apache.org/thread.html/r7b95bc248603360501f18c8eb03bb6001ec0ee3296205b34b07105b7%40%3Cusers.tomcat.apache.org%3E
https://lists.apache.org/thread.html/rcd90bf36b1877e1310b87ecd14ed7bbb15da52b297efd9f0e7253a3b%40%3Cusers.tomcat.apache.org%3E
https://lists.apache.org/thread.html/rd0463f9a5cbc02a485404c4b990f0da452e5ac5c237808edba11c947%40%3Cusers.tomcat.apache.org%3E
https://lists.apache.org/thread.html/rf6d5d57b114678d8898005faef31e9fd6d7c981fcc4ccfc3bc272fc9%40%3Cdev.tomcat.apache.org%3E
https://lists.debian.org/debian-lts-announce/2021/03/msg00018.html Mailing List, Third Party Advisory
https://security.gentoo.org/glsa/202208-34 Third Party Advisory
https://security.netapp.com/advisory/ntap-20210409-0002/ Third Party Advisory
https://www.debian.org/security/2021/dsa-4891 Third Party Advisory
https://www.oracle.com//security-alerts/cpujul2021.html Patch, Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.html Patch, Third Party Advisory
https://www.oracle.com/security-alerts/cpuoct2021.html Patch, Third Party Advisory