CVE-2026-54451 Elixir protobuf: Unbounded recursion depth in embedded-message decoding
Attackers can cause denial of service in Elixir applications by sending deeply nested protobuf messages that exhaust CPU and memory resources.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-54451?
CVE-2026-54451 is a high-severity denial of service vulnerability in elixir-protobuf protobuf, published on 17 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Elixir protobuf is a pure Elixir implementation of Google Protobuf. From 0.8.0 until 0.16.1, services that decode attacker-controlled protobuf bytes with Protobuf.Decoder can be taken offline when the schema contains a self-referential or cyclic message type. In lib/protobuf/decoder.ex, Protobuf.Decoder.value_for_field/3 handles an embedded?: true field by recursively entering the decode / build_message / handle_value / value_for_field call chain without enforcing a nesting-depth limit. Deeply nested embedded fields retain non-tail recursive frames, allowing a comparatively small request to consume substantial CPU and memory, pin a BEAM scheduler, and exhaust the node. This issue is fixed in version 0.16.1.
Weakness: CWE-674
Which versions are affected by CVE-2026-54451?
2 open source packages ship an affected version, including protobuf.
| Package | Affected | Fixed in |
|---|---|---|
protobuf Hex | From 0.8.0 | 0.16.1 |
protobuf Hex | From 0.8.0 | 0.16.1 |
How do I fix CVE-2026-54451?
Upgrade protobuf to 0.16.1 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-54451 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-54451 exists.
Sources
Also known as GHSA-rv48-qqj5-crxg, UBUNTU-CVE-2026-54451.