# CVE-2026-111821: Apache ActiveMQ, Apache ActiveMQ KahaDB: Oversized client identifier strings poison the KahaDB journal

Status: published. Published: 2026-11-04. Updated: 2026-11-04.

Improper input validation vulnerability in Apache ActiveMQ, Apache ActiveMQ KahaDB.



A user can create a durable subscription with a clientId and subscription name that have a combined length > 65,535 (while separately being shorter) on a broker using KahaDB which can cause the broker to shutdown and be unrecoverable. 



This issue affects Apache ActiveMQ: from 6.0.0 before 6.3.3, before 5.19.12; Apache ActiveMQ KahaDB: from 6.0.0 before 6.3.3, before 5.19.12.



Users are recommended to upgrade to version 6.4.0, 6.3.3 or 5.19.12, which fixes the issue.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Apache Software Foundation / Apache ActiveMQ (org.apache.activemq:apache-activemq): ≥ 6.0.0; < 6.3.3 (affected, semver); ≥ 0; < 5.19.12 (affected, semver). Source: CNA: apache
- Apache Software Foundation / Apache ActiveMQ KahaDB (org.apache.activemq:activemq-kahadb-store): ≥ 6.0.0; < 6.3.3 (affected, semver); ≥ 0; < 5.19.12 (affected, semver). Source: CNA: apache

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-20

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://lists.apache.org/thread/p8gxq66lmztkrls74wkz3xh9chqd0pwl (CNA: apache; vendor-advisory)

- http://www.openwall.com/lists/oss-security/2026/11/03/19 (ADP: CVE)

- https://lists.apache.org/thread/p8gxq66lmztkrls74wkz3xh9chqd0pwl (security@apache.org)

- http://www.openwall.com/lists/oss-security/2026/11/03/19 (af854a3a-2127-422b-91ae-364da2661108)

## Provenance

- CNA: apache: https://www.cve.org/CVERecord?id=CVE-2026-111821; retrieved 2026-11-04; source updated 2026-11-04

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-111821; retrieved 2026-11-04; source updated 2026-11-04

Revision: b3373de8422b8b3c8a2f7ac45d0eee702c98631b1ad043114991812da3949feb

Canonical: https://y2.dev/cve/CVE-2026-111821

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.