Description
There's a flaw in the zeromq server in versions before 4.3.3 in src/decoder_allocators.hpp. The decoder static allocator could have its sized changed, but the buffer would remain the same as it is a static buffer. A remote, unauthenticated attacker who sends a crafted request to the zeromq server could trigger a buffer overflow WRITE of arbitrary data if CURVE/ZAP authentication is not enabled. The greatest impact of this flaw is to application availability, data integrity, and confidentiality.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| — | zeromq | zeromq 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 9 | zeromq3 | 4.2.1-4+deb9u4 | DLA-2588-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 20.04 LTS | zeromq3 | 4.3.2-2ubuntu1.20.04.1~esm2 | USN-4920-1 |
| Ubuntu Pro 18.04 LTS | zeromq3 | 4.2.5-1ubuntu0.2+esm2 | USN-4920-1 |
| Ubuntu Pro 16.04 LTS | zeromq3 | 4.1.4-7ubuntu0.1+esm2 | 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+esm3 | USN-4920-1 |
Advisories 2
- USN-4920-1 zeromq3 vulnerabilities Ubuntu Security Notices (USN) · Jun 29, 2026
- DLA-2588-1 zeromq3 - security update Debian Security (DSA / DLA) · Mar 9, 2026