🛡️ CVE-2021-43980 on Debian — tomcat9

⚪ Unknown ✅ No Known Exploit OSV
N/A
CVSS Score
0 Low4 Medium7 High9 Critical10

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.

Distribution advisory

This page covers CVE-2021-43980 as tracked by Debian, for the package tomcat9. The fix is available in version 9.0.62-1; earlier versions remain affected.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality low, integrity none, availability none.

Weakness class

DEBIAN-CVE-2021-43980 is classified as CWE-362: Race Condition. Concurrent operations share state without proper synchronisation, so timing decides whether the result is correct.

Affected software

DEBIAN-CVE-2021-43980 is recorded against 1 package.

  • tomcat9 (fixed in 9.0.62-1)

Timeline and source

Published on 28 September 2022 and last revised on 4 August 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

security-tracker.debian.org (Advisory)

CVE-2021-43980 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity Unknown
CVSS Score N/A
CVSS Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2022-09-28
Updated 2026-08-12
Modified 2026-08-04
Fix URL N/A

Affected Packages

Software From version Fixed in
tomcat9 — 9.0.62-1

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