A pointer overflow, with code execution, was discovered in ZeroMQ libzmq (aka 0MQ) 4.2.x and 4.3.x before 4.3.1.
Noroxi assessment
Priority: Monitor (action score 38/100)
- Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
- Probability of exploitation in the next 30 days: 9.7% (FIRST EPSS); higher than 95.4% of all records.
- Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
- Fixed version: zeromq (Alpine:v3.10) 4.3.1-r0; zeromq (Alpine:v3.6) 4.2.5-r0; zeromq3 (Debian:12) 4.3.1-1.
Low priority for now. Upgrade to zeromq (Alpine:v3.10) 4.3.1-r0; zeromq (Alpine:v3.6) 4.2.5-r0; zeromq3 (Debian:12) 4.3.1-1 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
A pointer overflow, with code execution, was discovered in ZeroMQ libzmq (aka 0MQ) 4.2.x and 4.3.x before 4.3.1. A v2_decoder.cpp zmq::v2_decoder_t::size_ready integer overflow allows an authenticated attacker to overwrite an arbitrary amount of bytes beyond the bounds of a buffer, which can be leveraged to run arbitrary code on the target system. The memory layout allows the attacker to inject OS commands into a data structure located immediately after the problematic buffer (i.e., it is not necessary to use a typical buffer-overflow exploitation technique that changes the flow of control).
- Published
- Jan 13, 2019
- Updated
- Jun 16, 2026
- EPSS
- 9.7% · 95th percentile
- CWE
- CWE-190
Report tools
Action score
38
Monitor
Low priority for now.
- CVSS
- 35 / 40 · 8.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 3 / 30 · 9.7%
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- Proof of concept exists, no weaponized module
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- debian debian linux9.0
- zeromq libzmq4.2.0 and later · up to 4.2.5 inclusive
- zeromq libzmq4.3.0 and later · before 4.3.1
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Alpine:v3.10 | zeromq | before 4.3.1-r0 | 4.3.1-r0 |
| Alpine:v3.6 | zeromq | before 4.2.5-r0 | 4.2.5-r0 |
| Debian:12 | zeromq3 | before 4.3.1-1 | 4.3.1-1 |
| Debian:9 | zeromq3 | before 4.2.1-4+deb9u1 | 4.2.1-4+deb9u1 |
| openSUSE:Tumbleweed | python-pyzmq | before 27.1.0-3.1 | 27.1.0-3.1 |
| openSUSE:Tumbleweed | zeromq | before 4.3.4-2.2 | 4.3.4-2.2 |
| SUSE:Linux Enterprise Module for Basesystem 15 | zeromq | before 4.2.3-3.3.2 | 4.2.3-3.3.2 |
Same product
zeromq: all recordsOther highest-scoring records for the same primary product.
- CVE-2019-13132In ZeroMQ libzmq before 4.0.9, 4.1.x before 4.1.7, and 4.2.x before 4.3.2, a remote, unauthenticated client connecting to a libzmq applicati52Plan
- CVE-2021-20235There's a flaw in the zeromq server in versions before 4.3.3 in src/decoder_allocators.hpp.45Plan
- CVE-2020-36400ZeroMQ libzmq 4.3.3 has a heap-based buffer overflow in zmq::tcp_read, a different vulnerability than CVE-2021-20235.40Plan
- CVE-2021-20237An uncontrolled resource consumption (memory leak) flaw was found in ZeroMQ's src/xpub.cpp in versions before 4.3.3.31Monitor
- CVE-2020-15166Denial of Service in ZeroMQ31Monitor
- CVE-2021-20234An uncontrolled resource consumption (memory leak) flaw was found in the ZeroMQ client in versions before 4.3.3 in src/pipe.cpp.26Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| alpine:zeromq | 4.3.1-r0 · Alpine:v3.10 | Package registry (OSV) |
| debian:zeromq3 | 4.3.1-1 · Debian:12 | Package registry (OSV) |
| opensuse:python-pyzmq | 27.1.0-3.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| opensuse:zeromq | 4.3.4-2.2 · openSUSE:Tumbleweed | Package registry (OSV) |
| suse:zeromq | 4.2.3-3.3.2 · SUSE:Linux Enterprise Module for Basesystem 15 | Package registry (OSV) |
Exploit status
Proof of concept available
A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.
Evidence
- Proof-of-concept repository on GitHub ×2
Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.
| Source | Kind | Date |
|---|---|---|
| Proof-of-concept repository on GitHub | stars:1 | 2024-06-20 |
| Proof-of-concept repository on GitHub | stars:0 | 2026-05-03 |
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
- Published
- First PoC+1985 d
- TodayOct 16, 2026+2833 d
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- A low-privileged account is enough.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-190 · Integer Overflow or WraparoundCVSS vector
CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
—
Change log
- Fix✗ → ✓
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References
Show all references (2 more)Show less
Vendor advisories and official records. Exploit/PoC links are deliberately left out.