Home/CVE/The simplified implementation of blocking reads and writes introduced in Tomcat 10 and back-ported to Tomcat 9.0.47 onwa
CVE

CVE-2021-43980

The simplified implementation of blocking reads and writes introduced in Tomcat 10 and back-ported to Tomcat 9.0.47 onwa

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.

LOW · CVSS 3.7 EPSS 0.00203
Monitor
  • No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
Sigma rules1 YARA rules0
⬡

Weakness Classification

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
▤

Affected Products & Versions

5
apache tomcat>= 8.5.0 and <= 8.5.77
apache tomcat>= 9.0.0 and <= 9.0.60
apache tomcat>= 10.0.0 and <= 10.0.18
apache tomcatall versions
debian linuxall versions
▤

Affected Packages

1
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
Maven org.apache.tomcat:tomcat LOW fixed in 8.5.78
◈

Sigma Hunt Rules

1
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
productmediumTomcat WebServer Logs Deleted
▣

Scoring & Timeline

3.7
LOW · CVSS v3.1 · security@apache.org
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD28 Sep 2022 · 02:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
no
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

9
suse-csafSUSE-SU-2026:1058-1
suse-csafopenSUSE-SU-2024:12534-1
suse-csafopenSUSE-SU-2024:13441-1
suse-csafSUSE-SU-2022:4257-1
suse-csafSUSE-SU-2022:4221-1
🔗

References & Sources

4
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
http://www.openwall.com/lists/oss-security/2022/09/28/1Mailing ListThird Party Advisory
https://lists.apache.org/thread/3jjqbsp6j88b198x5rmg99b1qr8ht3g3Mailing ListVendor Advisory
https://lists.debian.org/debian-lts-announce/2022/10/msg00029.htmlMailing ListThird Party Advisory
https://www.debian.org/security/2022/dsa-5265Third Party Advisory
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