High 7.5Published Dec 3, 2020

CVE-2020-17527Apache Tomcat: Request header mix-up between HTTP/2 streams

Updated under an hour ago (Oct 27, 2026, 6:50 AM 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.

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Every CVE for Apache Software Foundation Apache Tomcat

Exploited in the last 30 days

While investigating bug 64830 it was discovered that Apache Tomcat 10.0.0-M1 to 10.0.0-M9, 9.0.0-M1 to 9.0.39 and 8.5.0 to 8.5.59 could re-use an HTTP request header value from the previous stream received on an HTTP/2 connection for the request associated with the subsequent stream. While this would most likely lead to an error and the closure of the HTTP/2 connection, it is possible that information could leak between requests.

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)	Apache Tomcat 10 10.0.0-M1 to 10.0.0-M9; Apache Tomcat 9 9.0.0-M1 to 9.0.39; Apache Tomcat 8.5 8.5.0 to 8.5.59	CNA record
apache tomcat apache:tomcat	from 8.5.1 through 8.5.59; from 9.0.1 through 9.0.35; 9.0.0; 9.0.0; 9.0.0; 9.0.0; 9.0.0; 9.0.0; and 32 more ranges	NVD
netapp element_plug-in netapp:element_plug-in	all versions	NVD
netapp oncommand_system_manager netapp:oncommand_system_manager	from 3.0.0 through 3.1.3	NVD
debian debian_linux debian:debian_linux	9.0; 10.0	NVD
oracle blockchain_platform oracle:blockchain_platform	before 21.1.2	NVD
oracle communications_cloud_native_core_binding_support_function oracle:communications_cloud_native_core_binding_support_function	1.10.0	NVD
oracle communications_cloud_native_core_policy oracle:communications_cloud_native_core_policy	1.14.0	NVD
oracle communications_instant_messaging_server oracle:communications_instant_messaging_server	10.0.1.5.0	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/rce5ac9a40173651d540babce59f6f3825f12c6d4e886ba00823b11e5%40%3Cannounce.tomcat.apache.org%3E	x-refsource-misc
https://lists.apache.org/thread.html/r8a227ac6a755a6406c1cc47dd48800e973d4cf13fe7fe68ac59c679c%40%3Cdev.tomcat.apache.org%3E	mailing-list, x-refsource-mlist
https://lists.apache.org/thread.html/raa0e9ad388c1e6fd1e301b5e080f9439f64cb4178119a86a4801cc53%40%3Cdev.tomcat.apache.org%3E	mailing-list, x-refsource-mlist
https://lists.apache.org/thread.html/rce5ac9a40173651d540babce59f6f3825f12c6d4e886ba00823b11e5%40%3Cannounce.apache.org%3E	mailing-list, x-refsource-mlist
https://lists.apache.org/thread.html/rd5babd13d7a350b369b2f647b4dd32ce678af42f9aba5389df1ae6ca%40%3Cusers.tomcat.apache.org%3E	mailing-list, x-refsource-mlist
http://www.openwall.com/lists/oss-security/2020/12/03/3	mailing-list, x-refsource-mlist
https://lists.apache.org/thread.html/rabbe6b3ae6a9795641d7a05c00d2378d5bbbe4240b7e20f09b092cce%40%3Cissues.guacamole.apache.org%3E	mailing-list, x-refsource-mlist
https://lists.apache.org/thread.html/ra35c8d617b17d59f400112cebadec43ad379f98198b4a9726190d7ee%40%3Cissues.guacamole.apache.org%3E	mailing-list, x-refsource-mlist
https://lists.apache.org/thread.html/r9fd47f1b03e9b41d16a5cf72659b533887267d3398d963c2fff3abfa%40%3Ccommits.tomee.apache.org%3E	mailing-list, x-refsource-mlist
https://lists.apache.org/thread.html/r26a2a66339087fc37db3caf201e446d3e83b5cce314371e235ff1784%40%3Ccommits.tomee.apache.org%3E	mailing-list, x-refsource-mlist
1–10 of 24

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.