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Advisory details: gitlab / maven/org.apache.tomcat.embed/tomcat-embed-core/CVE-2021-43980
Advisory ID gitlab/maven/org.apache.tomcat.embed/tomcat-embed-core/CVE-2021-43980
Aliases CVE-2021-43980
Summary Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') The simplified implementation of blocking reads and writes introduced in Tomcat 10 and back-ported to Tomcat 9.0.47 onwards exposed a long standing (but extremely hard to trigger) concurrency bug in Apache Tomcat 10.1.0 to 10.1.0-M12, 10.0.0-M1 to 10.0.18, 9.0.0-M1 to 9.0.60 and 8.5.0 to 8.5.77 that could cause client connections to share an Http11Processor instance resulting in responses, or part responses, to be received by the wrong client.
Status Published
Exploitability 0.5
Weighted Severity 0.0
Risk
Affected and Fixed Packages Package Details
Introduced and Fixed Package Commit Patches Package Commit Patches Details
Weaknesses (3)
CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CWE-937 OWASP Top Ten 2013 Category A9 - Using Components with Known Vulnerabilities
CWE-1035 OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
System Score Found at
cvssv3.1 https://gitlab.com/gitlab-org/advisories-community/-/blob/main/maven/org.apache.tomcat.embed/tomcat-embed-core/CVE-2021-43980.yml
Reference id Reference type URL
1 Mailing List http://www.openwall.com/lists/oss-security/2022/09/28/1
3jjqbsp6j88b198x5rmg99b1qr8ht3g3 Other https://lists.apache.org/thread/3jjqbsp6j88b198x5rmg99b1qr8ht3g3
CVE-2021-43980 https://nvd.nist.gov/vuln/detail/CVE-2021-43980
No exploits are available.

No EPSS data available for this advisory.

Patch URL
There are no known patches.
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N Found at https://gitlab.com/gitlab-org/advisories-community/-/blob/main/maven/org.apache.tomcat.embed/tomcat-embed-core/CVE-2021-43980.yml
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: SSVCv2/E:N/A:N/T:P/P:M/B:A/M:M/D:T/2025-05-21T14:59:33Z/

Decision: Track

Source URL: https://github.com/cisagov/vulnrichment/blob/develop/2021/43xxx/CVE-2021-43980.json

Source Advisory: vulnrichment/CVE-2021-43980

View SSVC decision tree 
[{'Exploitation': 'none'},
 {'Automatable': 'no'},
 {'Technical Impact': 'partial'},
 {'Mission Prevalence': 'minimal'},
 {'Public Well-being Impact': 'material'},
 {'Mission & Well-being': 'medium'}]