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tomcat9 — security advisory

Type: advisorySources: OSVAdvisory ID: DEBIAN-CVE-2021-43980

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.

Products
tomcat9
Affected versions
Not specified
Fixed versions
9.0.62-1
CVEs
CVE-2021-43980
Confirmed fixed CVEs
Not specified
Updated in this feed
1 Nov 2026, 01:07 UTC · Revision 1

Source evidence

DEBIAN-CVE-2021-43980

core-osv · Original source

Published 28 Sept 2022, 14:15 UTC

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.

osv:DEBIAN-CVE-2021-43980

tomcat9

Fixed versions: 9.0.62-1

tomcat9

Fixed versions: 9.0.62-1

tomcat9

Fixed versions: 9.0.62-1

Complete source record
{
  "id": "f16a0fdcf709330ba0c9a10b39ff849c50d943274e43317f37e262d162058002",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2021-43980",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2021-43980",
    "summary": "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.",
    "evidence": "osv:DEBIAN-CVE-2021-43980",
    "products": [
      {
        "name": {
          "value": "tomcat9",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "9.0.62-1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "tomcat9",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "9.0.62-1",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "tomcat9",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "9.0.62-1",
            "evidence": "/affected/2/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "low",
    "structured": {
      "id": "DEBIAN-CVE-2021-43980",
      "aliases": [
        "DEBIAN-CVE-2021-43980"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "9.0.62-1"
                }
              ]
            }
          ],
          "package": {
            "name": "tomcat9",
            "purl": "pkg:deb/debian/tomcat9?arch=source&distro=bookworm",
            "ecosystem": "Debian:12"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-43980.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "9.0.62-1"
                }
              ]
            }
          ],
          "package": {
            "name": "tomcat9",
            "purl": "pkg:deb/debian/tomcat9?arch=source&distro=trixie",
            "ecosystem": "Debian:13"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-43980.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "9.0.62-1"
                }
              ]
            }
          ],
          "package": {
            "name": "tomcat9",
            "purl": "pkg:deb/debian/tomcat9?arch=source&distro=forky",
            "ecosystem": "Debian:14"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-43980.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-23T18:04:16.658140003Z",
      "provider": "osv",
      "upstream": [
        "CVE-2021-43980"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2021-43980"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2021-43980",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 423114,
  "published_at": "2022-09-28T14:15:09.88+00:00"
}