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Vulnerability details: VCID-wptr-hkjx-s7c3
Vulnerability ID VCID-wptr-hkjx-s7c3
Aliases CVE-2021-42340
GHSA-wph7-x527-w3h5
Summary The fix for bug 63362 present in Apache Tomcat 10.1.0-M1 to 10.1.0-M5, 10.0.0-M1 to 10.0.11, 9.0.40 to 9.0.53 and 8.5.60 to 8.5.71 introduced a memory leak. The object introduced to collect metrics for HTTP upgrade connections was not released for WebSocket connections once the connection was closed. This created a memory leak that, over time, could lead to a denial of service via an OutOfMemoryError.
Status Published
Exploitability 0.5
Weighted Severity 8.0
Risk 4.0
Affected and Fixed Packages Package Details
Weaknesses (3)
CWE-1035 OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
CWE-772 Missing Release of Resource after Effective Lifetime
CWE-937 OWASP Top Ten 2013 Category A9 - Using Components with Known Vulnerabilities
System Score Found at
cvssv3 7.5 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-42340.json
epss 0.05703 https://api.first.org/data/v1/epss?cve=CVE-2021-42340
epss 0.05703 https://api.first.org/data/v1/epss?cve=CVE-2021-42340
epss 0.05703 https://api.first.org/data/v1/epss?cve=CVE-2021-42340
epss 0.05703 https://api.first.org/data/v1/epss?cve=CVE-2021-42340
epss 0.05703 https://api.first.org/data/v1/epss?cve=CVE-2021-42340
epss 0.05703 https://api.first.org/data/v1/epss?cve=CVE-2021-42340
epss 0.05703 https://api.first.org/data/v1/epss?cve=CVE-2021-42340
epss 0.05703 https://api.first.org/data/v1/epss?cve=CVE-2021-42340
apache_tomcat Important https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-42340
cvssv3.1_qr HIGH https://github.com/advisories/GHSA-wph7-x527-w3h5
cvssv3.1 7.5 https://github.com/apache/tomcat
generic_textual HIGH https://github.com/apache/tomcat
cvssv3.1 7.5 https://github.com/apache/tomcat/commit/31d62426645824bdfe076a0c0eafa904d90b4fb9
generic_textual HIGH https://github.com/apache/tomcat/commit/31d62426645824bdfe076a0c0eafa904d90b4fb9
cvssv3.1 7.5 https://github.com/apache/tomcat/commit/80f1438ec45e77a07b96419808971838d259eb47
generic_textual HIGH https://github.com/apache/tomcat/commit/80f1438ec45e77a07b96419808971838d259eb47
cvssv3.1 7.5 https://github.com/apache/tomcat/commit/d27535bdee95d252418201eb21e9d29476aa6b6a
generic_textual HIGH https://github.com/apache/tomcat/commit/d27535bdee95d252418201eb21e9d29476aa6b6a
cvssv3.1 7.5 https://github.com/apache/tomcat/commit/d5a6660cba7f51589468937bf3bbad4db7810371
generic_textual HIGH https://github.com/apache/tomcat/commit/d5a6660cba7f51589468937bf3bbad4db7810371
cvssv3.1 7.5 https://kc.mcafee.com/corporate/index?page=content&id=SB10379
generic_textual HIGH https://kc.mcafee.com/corporate/index?page=content&id=SB10379
cvssv3.1 7.5 https://lists.apache.org/thread.html/r8097a2d1550aa78e585fc77e602b9046e6d4099d8d132497c5387784@%3Ccommits.myfaces.apache.org%3E
generic_textual HIGH https://lists.apache.org/thread.html/r8097a2d1550aa78e585fc77e602b9046e6d4099d8d132497c5387784@%3Ccommits.myfaces.apache.org%3E
cvssv3.1 7.5 https://lists.apache.org/thread.html/r83a35be60f06aca2065f188ee542b9099695d57ced2e70e0885f905c%40%3Cannounce.tomcat.apache.org%3E
generic_textual HIGH https://lists.apache.org/thread.html/r83a35be60f06aca2065f188ee542b9099695d57ced2e70e0885f905c%40%3Cannounce.tomcat.apache.org%3E
cvssv3.1 7.5 https://nvd.nist.gov/vuln/detail/CVE-2021-42340
generic_textual HIGH https://nvd.nist.gov/vuln/detail/CVE-2021-42340
archlinux High https://security.archlinux.org/AVG-2469
archlinux High https://security.archlinux.org/AVG-2470
cvssv3.1 7.5 https://security.gentoo.org/glsa/202208-34
generic_textual HIGH https://security.gentoo.org/glsa/202208-34
cvssv3.1 7.5 https://security.netapp.com/advisory/ntap-20211104-0001
generic_textual HIGH https://security.netapp.com/advisory/ntap-20211104-0001
cvssv3.1 7.5 https://tomcat.apache.org/security-10.html
generic_textual HIGH https://tomcat.apache.org/security-10.html
cvssv3.1 7.5 https://tomcat.apache.org/security-8.html
generic_textual HIGH https://tomcat.apache.org/security-8.html
cvssv3.1 7.5 https://tomcat.apache.org/security-9.html
generic_textual HIGH https://tomcat.apache.org/security-9.html
cvssv3.1 7.5 https://www.debian.org/security/2021/dsa-5009
generic_textual HIGH https://www.debian.org/security/2021/dsa-5009
cvssv3.1 7.5 https://www.oracle.com/security-alerts/cpuapr2022.html
generic_textual HIGH https://www.oracle.com/security-alerts/cpuapr2022.html
cvssv3.1 7.5 https://www.oracle.com/security-alerts/cpujan2022.html
generic_textual HIGH https://www.oracle.com/security-alerts/cpujan2022.html
cvssv3.1 7.5 https://www.oracle.com/security-alerts/cpujul2022.html
generic_textual HIGH https://www.oracle.com/security-alerts/cpujul2022.html
Reference id Reference type URL
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-42340.json
https://api.first.org/data/v1/epss?cve=CVE-2021-42340
https://github.com/apache/tomcat
https://github.com/apache/tomcat/commit/31d62426645824bdfe076a0c0eafa904d90b4fb9
https://github.com/apache/tomcat/commit/80f1438ec45e77a07b96419808971838d259eb47
https://github.com/apache/tomcat/commit/d27535bdee95d252418201eb21e9d29476aa6b6a
https://github.com/apache/tomcat/commit/d5a6660cba7f51589468937bf3bbad4db7810371
https://kc.mcafee.com/corporate/index?page=content&id=SB10379
https://lists.apache.org/thread.html/r8097a2d1550aa78e585fc77e602b9046e6d4099d8d132497c5387784@%3Ccommits.myfaces.apache.org%3E
https://lists.apache.org/thread.html/r83a35be60f06aca2065f188ee542b9099695d57ced2e70e0885f905c%40%3Cannounce.tomcat.apache.org%3E
https://security.gentoo.org/glsa/202208-34
https://security.netapp.com/advisory/ntap-20211104-0001
https://tomcat.apache.org/security-10.html
https://tomcat.apache.org/security-8.html
https://tomcat.apache.org/security-9.html
https://www.debian.org/security/2021/dsa-5009
https://www.oracle.com/security-alerts/cpuapr2022.html
https://www.oracle.com/security-alerts/cpujan2022.html
https://www.oracle.com/security-alerts/cpujul2022.html
2014356 https://bugzilla.redhat.com/show_bug.cgi?id=2014356
AVG-2469 https://security.archlinux.org/AVG-2469
AVG-2470 https://security.archlinux.org/AVG-2470
CVE-2021-42340 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-42340
CVE-2021-42340 https://nvd.nist.gov/vuln/detail/CVE-2021-42340
GHSA-wph7-x527-w3h5 https://github.com/advisories/GHSA-wph7-x527-w3h5
RHSA-2021:4861 https://access.redhat.com/errata/RHSA-2021:4861
RHSA-2021:4863 https://access.redhat.com/errata/RHSA-2021:4863
RHSA-2022:1179 https://access.redhat.com/errata/RHSA-2022:1179
RHSA-2022:5532 https://access.redhat.com/errata/RHSA-2022:5532
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-42340.json
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://github.com/apache/tomcat
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://github.com/apache/tomcat/commit/31d62426645824bdfe076a0c0eafa904d90b4fb9
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://github.com/apache/tomcat/commit/80f1438ec45e77a07b96419808971838d259eb47
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://github.com/apache/tomcat/commit/d27535bdee95d252418201eb21e9d29476aa6b6a
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://github.com/apache/tomcat/commit/d5a6660cba7f51589468937bf3bbad4db7810371
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

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required

unchanged

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://kc.mcafee.com/corporate/index?page=content&id=SB10379
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

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required

unchanged

changed

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://lists.apache.org/thread.html/r8097a2d1550aa78e585fc77e602b9046e6d4099d8d132497c5387784@%3Ccommits.myfaces.apache.org%3E
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

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low

none

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://lists.apache.org/thread.html/r83a35be60f06aca2065f188ee542b9099695d57ced2e70e0885f905c%40%3Cannounce.tomcat.apache.org%3E
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

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required

unchanged

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://nvd.nist.gov/vuln/detail/CVE-2021-42340
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

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unchanged

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://security.gentoo.org/glsa/202208-34
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

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required

unchanged

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://security.netapp.com/advisory/ntap-20211104-0001
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://tomcat.apache.org/security-10.html
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

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required

unchanged

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low

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none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://tomcat.apache.org/security-8.html
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

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required

unchanged

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high

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low

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://tomcat.apache.org/security-9.html
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://www.debian.org/security/2021/dsa-5009
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://www.oracle.com/security-alerts/cpuapr2022.html
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://www.oracle.com/security-alerts/cpujan2022.html
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://www.oracle.com/security-alerts/cpujul2022.html
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

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unchanged

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Exploit Prediction Scoring System (EPSS)
Percentile 0.90377
EPSS Score 0.05703
Published At April 1, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-04-01T12:38:06.129071+00:00 Apache Tomcat Importer Import https://tomcat.apache.org/security-10.html 38.0.0