Description
In ZeroMQ before version 4.3.3, there is a denial-of-service vulnerability. Users with TCP transport public endpoints, even with CURVE/ZAP enabled, are impacted. If a raw TCP socket is opened and connected to an endpoint that is fully configured with CURVE/ZAP, legitimate clients will not be able to exchange any message. Handshakes complete successfully, and messages are delivered to the library, but the server application never receives them. This is patched in version 4.3.3.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| zeromq | libzmq | < 4.3.3 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | zeromq3 | 4.3.3-1 | — |
| Debian 13 | zeromq3 | 4.3.3-1 | — |
| Debian 12 | zeromq3 | 4.3.3-1 | — |
| Debian 10 | zeromq3 | 4.3.1-4+deb10u2 | DSA-4761-1 |
| Debian 9 | zeromq3 | 4.2.1-4+deb9u3 | DLA-2443-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 20.04 LTS | zeromq3 | 4.3.2-2ubuntu1.20.04.1~esm1 | USN-4920-1 |
| Ubuntu Pro 18.04 LTS | zeromq3 | 4.2.5-1ubuntu0.2+esm1 | USN-4920-1 |
| Ubuntu Pro 16.04 LTS | zeromq3 | 4.1.4-7ubuntu0.1+esm1 | USN-4920-1 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 14.04 LTS | zeromq3 | 4.0.4+dfsg-2ubuntu0.1+esm2 | USN-4920-1 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP2 | libunwind | 1.2.1-4.2.3 | SUSE-SU-2020:3264-1 |
| SLES 15 SP2 | zeromq | 4.2.3-3.15.4 | SUSE-SU-2020:3264-1 |
| SLES 15 SP1 | libunwind | 1.2.1-4.2.3 | SUSE-SU-2020:3264-1 |
| SLES 15 SP1 | zeromq | 4.2.3-3.15.4 | SUSE-SU-2020:3264-1 |
| SLES 15 | libunwind | 1.2.1-4.2.3 | SUSE-SU-2020:3264-1 |
| SLES 15 | zeromq | 4.2.3-3.15.4 | SUSE-SU-2020:3264-1 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 15 | libunwind | 1.2.1-4.2.3 | SUSE-SU-2020:3264-1 |
| SLES for SAP 15 | zeromq | 4.2.3-3.15.4 | SUSE-SU-2020:3264-1 |
| SLE HPC 15 | libunwind | 1.2.1-4.2.3 | SUSE-SU-2020:3264-1 |
| SLE HPC 15 | zeromq | 4.2.3-3.15.4 | SUSE-SU-2020:3264-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | zeromq | 4.3.4-2.2 | openSUSE-SU-2024:11540-1 |
| openSUSE Leap 15.2 | libunwind | 1.2.1-lp152.5.3.1 | openSUSE-SU-2020:1910-1 |
| openSUSE Leap 15.2 | zeromq | 4.2.3-lp152.7.3.1 | openSUSE-SU-2020:1910-1 |
| openSUSE Leap 15.1 | libunwind | 1.2.1-lp151.4.3.1 | openSUSE-SU-2020:1907-1 |
| openSUSE Leap 15.1 | zeromq | 4.2.3-lp151.5.6.1 | openSUSE-SU-2020:1907-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | zeromq | 4.3.3-r0 | — |
| Alpine v3.23 | zeromq | 4.3.3-r0 | — |
| Alpine v3.22 | zeromq | 4.3.3-r0 | — |
| Alpine v3.21 | zeromq | 4.3.3-r0 | — |
| Alpine v3.20 | zeromq | 4.3.3-r0 | — |
Show 11 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | zeromq | 4.3.3-r0 | — |
| Alpine v3.18 | zeromq | 4.3.3-r0 | — |
| Alpine v3.17 | zeromq | 4.3.3-r0 | — |
| Alpine v3.16 | zeromq | 4.3.3-r0 | — |
| Alpine v3.15 | zeromq | 4.3.3-r0 | — |
| Alpine v3.14 | zeromq | 4.3.3-r0 | — |
| Alpine v3.13 | zeromq | 4.3.3-r0 | — |
| Alpine v3.12 | zeromq | 4.3.3-r0 | — |
| Alpine v3.11 | zeromq | 4.3.3-r0 | — |
| Alpine v3.10 | zeromq | 4.3.3-r0 | — |
| Alpine v3.9 | zeromq | 4.3.3-r0 | — |
Advisories 7
- USN-4920-1 zeromq3 vulnerabilities Ubuntu Security Notices (USN) · Jun 29, 2026
- DSA-4761-1 zeromq3 - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-2443-1 zeromq3 - security update Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2024:11540-1 libzmq5-32bit-4.3.4-2.2 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:3264-1 Security update for zeromq SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2020:1910-1 Security update for zeromq SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2020:1907-1 Security update for zeromq SUSE / openSUSE Security Updates · Feb 4, 2026
References
- https://github.com/zeromq/libzmq/security/advisories/GHSA-25wp-cf8g-938m
- https://github.com/zeromq/libzmq/pull/3913
- https://github.com/zeromq/libzmq/pull/3973
- GLSA-202009-12 vendor-advisory
- FEDORA-2020-08402f4071 vendor-advisory
- FEDORA-2020-5460fcf6bd vendor-advisory
- [debian-lts-announce] 20201110 [SECURITY] [DLA 2443-1] zeromq3 security update mailing-list