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

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.

Published: 2021-03-01 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-25122 is rated High Risk (68.9/100): CVSS High severity, with high exploitation likelihood (EPSS 18.11%, 97th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +15.34% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-25122

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 2.77% 18.11% +15.34%
2 2026-05-20 2.56% 2.77% +0.21%
3 2026-03-28 — 2.56% —

Full EPSS history (54 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-25122

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:P/I:N/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:N)
No availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2021-25122

GitHub Security Advisory for CVE-2021-25122

GHSA-j39c-c8hj-x4j3 · Severity: high · Ecosystem: maven — Exposure of Sensitive Information to an Unauthorized Actor in Apache Tomcat

OS Trackers for CVE-2021-25122

vendor priority summary link
debian not yet assigned CVE-2021-25122 not yet assigned priority: Debian including 1 source packages (tomcat9), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-25122
gentoo low CVE-2021-25122: 1 GLSA(s) (202208-34), 1 atom(s) (www-servers/tomcat); latest impact low. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-25122
redhat medium — https://access.redhat.com/security/cve/CVE-2021-25122
suse high CVE-2021-25122 severity important: SUSE including 360 source package names (5.0.0-beta1.2.122:tomcat-9.0.36-3.24.1, 5.0.0-beta1.2.122:tomcat-el-3_0-api-9.0.36-3.24.1, …), 723 product×package rows across 71 product lines (Container containers/apache-tomcat, Container suse/manager/5.0/x86_64/server, … (71 product lines)): Fixed 378, Known Affected 231, Known Not Affected 114. https://www.suse.com/security/cve/CVE-2021-25122/
ubuntu medium CVE-2021-25122 medium priority: Ubuntu including 4 source packages (tomcat6, tomcat7, tomcat8, tomcat9), 52 status rows across 13 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, trusty, upstream, xenial): DNE 31, not-affected 10, ignored 6, released 3, needs-triage 2. https://ubuntu.com/security/CVE-2021-25122

Affected software / configurations for CVE-2021-25122

Vendor Product Version Raw CPE
apache tomcat >= 8.5.0, <= 8.5.61 cpe:2.3:a:apache:tomcat:*:*:*:*:*:*:*:*
apache tomcat >= 9.0.0, <= 9.0.41 cpe:2.3:a:apache:tomcat:*:*:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone1:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone10:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone11:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone12:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone13:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone14:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone15:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone16:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone17:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone18:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone19:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone2:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone20:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone21:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone22:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone23:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone24:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone25:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone26:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone27:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone3:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone4:*:*:*:*:*:*
apache tomcat 9.0.0 cpe:2.3:a:apache:tomcat:9.0.0:milestone5:*:*:*:*:*:*
apache tomcat 10.0.0 cpe:2.3:a:apache:tomcat:10.0.0:-:*:*:*:*:*:*
apache tomcat 10.0.0 cpe:2.3:a:apache:tomcat:10.0.0:milestone1:*:*:*:*:*:*
apache tomcat 10.0.0 cpe:2.3:a:apache:tomcat:10.0.0:milestone10:*:*:*:*:*:*
apache tomcat 10.0.0 cpe:2.3:a:apache:tomcat:10.0.0:milestone2:*:*:*:*:*:*
apache tomcat 10.0.0 cpe:2.3:a:apache:tomcat:10.0.0:milestone3:*:*:*:*:*:*
apache tomcat 10.0.0 cpe:2.3:a:apache:tomcat:10.0.0:milestone4:*:*:*:*:*:*
apache tomcat 10.0.0 cpe:2.3:a:apache:tomcat:10.0.0:milestone5:*:*:*:*:*:*
apache tomcat 10.0.0 cpe:2.3:a:apache:tomcat:10.0.0:milestone6:*:*:*:*:*:*
apache tomcat 10.0.0 cpe:2.3:a:apache:tomcat:10.0.0:milestone7:*:*:*:*:*:*
apache tomcat 10.0.0 cpe:2.3:a:apache:tomcat:10.0.0:milestone8:*:*:*:*:*:*
apache tomcat 10.0.0 cpe:2.3:a:apache:tomcat:10.0.0:milestone9:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
oracle agile_plm 9.3.3 cpe:2.3:a:oracle:agile_plm:9.3.3:*:*:*:*:*:*:*
oracle agile_plm 9.3.6 cpe:2.3:a:oracle:agile_plm:9.3.6:*:*:*:*:*:*:*
oracle communications_cloud_native_core_policy 1.14.0 cpe:2.3:a:oracle:communications_cloud_native_core_policy:1.14.0:*:*:*:*:*:*:*
oracle communications_cloud_native_core_security_edge_protection_proxy 1.6.0 cpe:2.3:a:oracle:communications_cloud_native_core_security_edge_protection_proxy:1.6.0:*:*:*:*:*:*:*
oracle communications_instant_messaging_server 10.0.1.5.0 cpe:2.3:a:oracle:communications_instant_messaging_server:10.0.1.5.0:*:*:*:*:*:*:*
oracle database 12.2.0.1 cpe:2.3:a:oracle:database:12.2.0.1:*:*:*:enterprise:*:*:*
oracle database 19c cpe:2.3:a:oracle:database:19c:*:*:*:enterprise:*:*:*
oracle database 21c cpe:2.3:a:oracle:database:21c:*:*:*:enterprise:*:*:*
oracle graph_server_and_client < 21.3.0 cpe:2.3:a:oracle:graph_server_and_client:*:*:*:*:*:*:*:*
oracle graph_server_and_client 21.3.0 cpe:2.3:a:oracle:graph_server_and_client:21.3.0:*:*:*:*:*:*:*
oracle instantis_enterprisetrack 17.1 cpe:2.3:a:oracle:instantis_enterprisetrack:17.1:*:*:*:*:*:*:*
oracle instantis_enterprisetrack 17.2 cpe:2.3:a:oracle:instantis_enterprisetrack:17.2:*:*:*:*:*:*:*
oracle instantis_enterprisetrack 17.3 cpe:2.3:a:oracle:instantis_enterprisetrack:17.3:*:*:*:*:*:*:*
oracle managed_file_transfer 12.2.1.3.0 cpe:2.3:a:oracle:managed_file_transfer:12.2.1.3.0:*:*:*:*:*:*:*
oracle managed_file_transfer 12.2.1.4.0 cpe:2.3:a:oracle:managed_file_transfer:12.2.1.4.0:*:*:*:*:*:*:*
oracle mysql_enterprise_monitor <= 8.0.23 cpe:2.3:a:oracle:mysql_enterprise_monitor:*:*:*:*:*:*:*:*
oracle siebel_ui_framework <= 21.9 cpe:2.3:a:oracle:siebel_ui_framework:*:*:*:*:*:*:*:*

References for CVE-2021-25122

URL Tags
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%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
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