What’s Vulnerable › Vulnerabilities

CVE-2021-43980: Apache Tomcat: Information disclosure

• Severity: low (CVSS 3.7 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2022-09-28 · updated 2026-06-17
• Weakness: CWE-362

Description

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.

Affected products

• Apache Tomcat: from 8.5.0 through 8.5.77; from 9.0.0 through 9.0.60; from 10.0.0 through 10.0.18; 10.1.0-milestone1, 10.1.0-milestone10, 10.1.0-milestone11, 10.1.0-milestone12, 10.1.0-milestone2, 10.1.0-milestone3 (+6)
• Debian Linux: 10.0, 11.0

References

• http://www.openwall.com/lists/oss-security/2022/09/28/1
• https://lists.apache.org/thread/3jjqbsp6j88b198x5rmg99b1qr8ht3g3
• https://lists.debian.org/debian-lts-announce/2022/10/msg00029.html
• https://www.debian.org/security/2022/dsa-5265
• http://www.openwall.com/lists/oss-security/2022/09/28/1
• https://lists.apache.org/thread/3jjqbsp6j88b198x5rmg99b1qr8ht3g3
• https://lists.debian.org/debian-lts-announce/2022/10/msg00029.html
• https://www.debian.org/security/2022/dsa-5265

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