--- id: CVE-2020-17527 title: >- 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… summary: >- 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… severity: high cvss: 7.5 cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N' cwe: - CWE-200 - CWE-200 vendor: apache product: tomcat affected: - 'tomcat >= 8.5.1, <= 8.5.59' - 'tomcat >= 9.0.1, <= 9.0.35' - tomcat = 9.0.0 - tomcat = 9.0.35-3.39.1 - tomcat = 9.0.35-3.57.3 - tomcat = 9.0.36 - tomcat = 9.0.37 - tomcat = 9.0.38 - tomcat = 9.0.39 - tomcat = 10.0.0 - element_plug-in - 'oncommand_system_manager >= 3.0.0, <= 3.1.3' - debian_linux = 9.0 - debian_linux = 10.0 - blockchain_platform < 21.1.2 - communications_cloud_native_core_binding_support_function = 1.10.0 - communications_cloud_native_core_policy = 1.14.0 - communications_instant_messaging_server = 10.0.1.5.0 - instantis_enterprisetrack = 17.1 - instantis_enterprisetrack = 17.2 - instantis_enterprisetrack = 17.3 - mysql_enterprise_monitor < 8.0.23 - sd-wan_edge = 9.0 - workload_manager = 18c - workload_manager = 19c patched: - blockchain_platform 21.1.2 - mysql_enterprise_monitor 8.0.23 published: '2020-12-03' updated: '2026-10-08' sourceUpdated: '2026-10-08T22:16:57.557' source: NVD sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2020-17527' references: - url: 'http://www.openwall.com/lists/oss-security/2020/12/03/3' label: security@apache.org - url: >- https://lists.apache.org/thread.html/r26a2a66339087fc37db3caf201e446d3e83b5cce314371e235ff1784%40%3Ccommits.tomee.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/r2d6e05c5ff96f8068a59dfdb3800e9ee8d4e36ce1971783c6e5f9b20%40%3Ccommits.tomee.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/r5a285242737ddef4d338236328aaaf3237183e1465a5efafd16b99ed%40%3Cdev.tomcat.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/r8a227ac6a755a6406c1cc47dd48800e973d4cf13fe7fe68ac59c679c%40%3Cdev.tomcat.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/r9fd47f1b03e9b41d16a5cf72659b533887267d3398d963c2fff3abfa%40%3Ccommits.tomee.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/ra35c8d617b17d59f400112cebadec43ad379f98198b4a9726190d7ee%40%3Cissues.guacamole.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/ra9fcdb904dd2e2256ef90b3e4ced279cd464cb0ab63a6c64df5c010d%40%3Cannounce.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/ra9fcdb904dd2e2256ef90b3e4ced279cd464cb0ab63a6c64df5c010d%40%3Cannounce.tomcat.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/raa0e9ad388c1e6fd1e301b5e080f9439f64cb4178119a86a4801cc53%40%3Cdev.tomcat.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/rabbe6b3ae6a9795641d7a05c00d2378d5bbbe4240b7e20f09b092cce%40%3Cissues.guacamole.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/rbba08c4dcef3603e36276d49adda8eedbe458c5104314b4038f697e1%40%3Cusers.tomcat.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/rca833c6d42b7b9ce1563488c0929f29fcc95947d86e5e740258c8937%40%3Cdev.tomcat.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/rce5ac9a40173651d540babce59f6f3825f12c6d4e886ba00823b11e5%40%3Cannounce.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/rce5ac9a40173651d540babce59f6f3825f12c6d4e886ba00823b11e5%40%3Cannounce.tomcat.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/rce5ac9a40173651d540babce59f6f3825f12c6d4e886ba00823b11e5%40%3Cannounce.tomcat.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/rce5ac9a40173651d540babce59f6f3825f12c6d4e886ba00823b11e5%40%3Cannounce.tomcat.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/rce5ac9a40173651d540babce59f6f3825f12c6d4e886ba00823b11e5%40%3Cannounce.tomcat.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/rce5ac9a40173651d540babce59f6f3825f12c6d4e886ba00823b11e5%40%3Cannounce.tomcat.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/rce5ac9a40173651d540babce59f6f3825f12c6d4e886ba00823b11e5%40%3Cannounce.tomcat.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/rce5ac9a40173651d540babce59f6f3825f12c6d4e886ba00823b11e5%40%3Cannounce.tomcat.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/rce5ac9a40173651d540babce59f6f3825f12c6d4e886ba00823b11e5%40%3Cannounce.tomcat.apache.org%3E label: security@apache.org - url: >- https://lists.apache.org/thread.html/rd5babd13d7a350b369b2f647b4dd32ce678af42f9aba5389df1ae6ca%40%3Cusers.tomcat.apache.org%3E label: security@apache.org - url: 'https://lists.debian.org/debian-lts-announce/2020/12/msg00022.html' label: security@apache.org - url: 'https://security.gentoo.org/glsa/202012-23' label: security@apache.org - url: 'https://security.netapp.com/advisory/ntap-20201210-0003/' label: security@apache.org - url: 'https://www.debian.org/security/2021/dsa-4835' label: security@apache.org - url: 'https://www.oracle.com//security-alerts/cpujul2021.html' label: security@apache.org - url: 'https://www.oracle.com/security-alerts/cpuApr2021.html' label: security@apache.org - url: 'https://www.oracle.com/security-alerts/cpuapr2022.html' label: security@apache.org - url: 'https://www.oracle.com/security-alerts/cpujan2022.html' label: security@apache.org - url: 'http://www.openwall.com/lists/oss-security/2020/12/03/3' label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/r26a2a66339087fc37db3caf201e446d3e83b5cce314371e235ff1784%40%3Ccommits.tomee.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/r2d6e05c5ff96f8068a59dfdb3800e9ee8d4e36ce1971783c6e5f9b20%40%3Ccommits.tomee.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/r5a285242737ddef4d338236328aaaf3237183e1465a5efafd16b99ed%40%3Cdev.tomcat.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/r8a227ac6a755a6406c1cc47dd48800e973d4cf13fe7fe68ac59c679c%40%3Cdev.tomcat.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/r9fd47f1b03e9b41d16a5cf72659b533887267d3398d963c2fff3abfa%40%3Ccommits.tomee.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/ra35c8d617b17d59f400112cebadec43ad379f98198b4a9726190d7ee%40%3Cissues.guacamole.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/ra9fcdb904dd2e2256ef90b3e4ced279cd464cb0ab63a6c64df5c010d%40%3Cannounce.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/ra9fcdb904dd2e2256ef90b3e4ced279cd464cb0ab63a6c64df5c010d%40%3Cannounce.tomcat.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/raa0e9ad388c1e6fd1e301b5e080f9439f64cb4178119a86a4801cc53%40%3Cdev.tomcat.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/rabbe6b3ae6a9795641d7a05c00d2378d5bbbe4240b7e20f09b092cce%40%3Cissues.guacamole.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/rbba08c4dcef3603e36276d49adda8eedbe458c5104314b4038f697e1%40%3Cusers.tomcat.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/rca833c6d42b7b9ce1563488c0929f29fcc95947d86e5e740258c8937%40%3Cdev.tomcat.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/rce5ac9a40173651d540babce59f6f3825f12c6d4e886ba00823b11e5%40%3Cannounce.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/rce5ac9a40173651d540babce59f6f3825f12c6d4e886ba00823b11e5%40%3Cannounce.tomcat.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/rce5ac9a40173651d540babce59f6f3825f12c6d4e886ba00823b11e5%40%3Cannounce.tomcat.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/rce5ac9a40173651d540babce59f6f3825f12c6d4e886ba00823b11e5%40%3Cannounce.tomcat.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/rce5ac9a40173651d540babce59f6f3825f12c6d4e886ba00823b11e5%40%3Cannounce.tomcat.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/rce5ac9a40173651d540babce59f6f3825f12c6d4e886ba00823b11e5%40%3Cannounce.tomcat.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/rce5ac9a40173651d540babce59f6f3825f12c6d4e886ba00823b11e5%40%3Cannounce.tomcat.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/rce5ac9a40173651d540babce59f6f3825f12c6d4e886ba00823b11e5%40%3Cannounce.tomcat.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/rce5ac9a40173651d540babce59f6f3825f12c6d4e886ba00823b11e5%40%3Cannounce.tomcat.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/rd5babd13d7a350b369b2f647b4dd32ce678af42f9aba5389df1ae6ca%40%3Cusers.tomcat.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://lists.debian.org/debian-lts-announce/2020/12/msg00022.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://security.gentoo.org/glsa/202012-23' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://security.netapp.com/advisory/ntap-20201210-0003/' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://www.debian.org/security/2021/dsa-4835' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://www.oracle.com//security-alerts/cpujul2021.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://www.oracle.com/security-alerts/cpuApr2021.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://www.oracle.com/security-alerts/cpuapr2022.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://www.oracle.com/security-alerts/cpujan2022.html' label: af854a3a-2127-422b-91ae-364da2661108 tags: - nvd - exploit-available epss: 0.24622 epssPercentile: 0.97836 exploits: github: 1 githubRepos: - 'https://github.com/forse01/CVE-2020-17527-Tomcat' checkedAt: '2026-10-08T23:17:21.747Z' exploitAvailable: true ingestedAt: '2026-10-08T23:16:47.310Z' --- ## Overview 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. ## Affected - `tomcat >= 8.5.1, <= 8.5.59` - `tomcat >= 9.0.1, <= 9.0.35` - `tomcat = 9.0.0` - `tomcat = 9.0.35-3.39.1` - `tomcat = 9.0.35-3.57.3` - `tomcat = 9.0.36` - `tomcat = 9.0.37` - `tomcat = 9.0.38` - `tomcat = 9.0.39` - `tomcat = 10.0.0` - `element_plug-in` - `oncommand_system_manager >= 3.0.0, <= 3.1.3` - `debian_linux = 9.0` - `debian_linux = 10.0` - `blockchain_platform < 21.1.2` - `communications_cloud_native_core_binding_support_function = 1.10.0` - `communications_cloud_native_core_policy = 1.14.0` - `communications_instant_messaging_server = 10.0.1.5.0` - `instantis_enterprisetrack = 17.1` - `instantis_enterprisetrack = 17.2` - `instantis_enterprisetrack = 17.3` - `mysql_enterprise_monitor < 8.0.23` - `sd-wan_edge = 9.0` - `workload_manager = 18c` - `workload_manager = 19c` ## Remediation Upgrade past the affected range: - `blockchain_platform 21.1.2` - `mysql_enterprise_monitor 8.0.23`