Buffer overflow in zeromq
Priority MEDIUM 46CWE-120Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Will not fix Red Hat: no fix planned
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-120 and the CVSS impact.
Summary
A flaw was found in the ZeroMQ server in versions before 4.3.3. This flaw allows a malicious client to cause a stack buffer overflow on the server by sending crafted topic subscription requests and then unsubscribing. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.
Why it matters now
EPSS 0.01868 79th percentileScored 2026-11-07
Fix Will not fix Red Hat: no fix planned
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | zeromq | zeromq 4.3.3 | — | No fix listed | CNA |
- zeromq Vendor— Affected zeromq 4.3.3 Fixed in — No fix listed CNA
CPE configurations NVD · 4
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:zeromq:zeromq:*:*:*:*:*:*:*:* | before 4.3.3 | Vulnerable | zeromq |
| cpe:2.3:a:redhat:ceph_storage:2.0:*:*:*:*:*:*:* | 2.0 | Vulnerable | Red Hat |
| cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:* | 7.0 | Vulnerable | Red Hat |
| cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:* | 33 | Vulnerable | Fedoraproject |
- cpe:2.3:a:zeromq:zeromq:*:*:*:*:*:*:*:* Versions before 4.3.3 Vulnerable ·zeromq
- cpe:2.3:a:redhat:ceph_storage:2.0:*:*:*:*:*:*:* Versions 2.0 Vulnerable ·Red Hat
- cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:* Versions 7.0 Vulnerable ·Red Hat
- cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:* Versions 33 Vulnerable ·Fedoraproject
Remediation
No fixed version listed by the sources yet.
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Ceph Storage 2 | Affected | No fix planned: Out of support scope |
Timeline
- 2026-10-02 Threatist record created from CVE-2021-20236
- 2026-10-03 Alias added: GHSA-4j25-p3vq-p264
References
Sources
- CVE-2021-20236 · CVE Program
- CVE-2021-20236 · NVD
- FIRST EPSS
- GHSA-4j25-p3vq-p264 · GitHub Advisory Database · CC BY 4.0
- CVE-2021-20236 · Red Hat security data · CC BY 4.0
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