# CVE-2026-119434: Decompression bomb in ezstd:decompress_using_ddict/2 allows BEAM memory exhaustion via unbounded output buffer


- **Severity:** Medium 6.9 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 5 Nov 2026
- **Updated:** 5 Nov 2026
- **Also known as:** EEF-CVE-2026-119434, GHSA-p9j8-93gx-5h3x

## What is CVE-2026-119434?

CVE-2026-119434 is a medium-severity vulnerability in silviucpp ezstd, published on 5 Nov 2026. 

### Official description

Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in silviucpp ezstd allows an attacker who supplies a zstd frame to ezstd:decompress_using_ddict/2 to exhaust memory and terminate the Erlang VM via a small frame that declares a very large content size.

zstd_nif_decompress_using_ddict in c_src/ezstd_nif.cc reads the frame's declared content size with ZSTD_getFrameContentSize and passes it directly to enif_make_new_binary, without the 1 GiB MAX_BUFFER_SIZE check that ezstd:decompress/1 applies before allocating. A valid 65,550-byte frame of RLE blocks declaring 2 GiB is rejected by ezstd:decompress/1 but is fully allocated and decompressed by the dictionary path. The allocation happens inside a NIF, so when it exceeds the memory available to the VM the operating system kills the whole node rather than the calling process.

This issue affects ezstd: from 1.0.5 before 1.2.5.

Weakness: CWE-409 (Improper Handling of Highly Compressed Data (Data Amplification))

## Which versions are affected by CVE-2026-119434?

1 open source package ship an affected version, including ezstd.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `ezstd` | Hex | From 1.0.5 | 1.2.5 |

## How do I fix CVE-2026-119434?

Upgrade ezstd to 1.2.5 or later.

## Is CVE-2026-119434 being exploited?

There is no known exploitation of CVE-2026-119434 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-119434 and fix it if it is affected.

What it is: CVE-2026-119434 is a medium-severity vulnerability in silviucpp ezstd, published on 5 Nov 2026. 
Exploitation: There is no known exploitation of CVE-2026-119434 in the wild and no public exploit code.

Affected packages and fixed versions:
- ezstd (Hex): affected from 1.0.5; fixed in 1.2.5

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-119434/ (Markdown: https://insights.sbomify.com/CVE-2026-119434/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-119434
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-119434
- OSV: https://osv.dev/vulnerability/CVE-2026-119434

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-119434/
Summaries are generated and may contain mistakes; the official description above is the record.