# CVE-2026-62357: DragonflyDB `CMS.INITBYDIM` integer overflow leads to a remote, attacker-controlled heap out-of-bounds write

> An integer overflow in DragonflyDB allows remote attackers to trigger heap out-of-bounds writes, potentially leading to code execution or server crashes.

- **Severity:** High 8.8 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 18 Aug 2026
- **Updated:** 19 Aug 2026
- **Also known as:** GHSA-cmmv-h748-v93x

## What is CVE-2026-62357?

CVE-2026-62357 is a high-severity vulnerability in dragonflydb dragonfly, published on 18 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Dragonfly is an in-memory data store built for modern application workloads. Prior to 1.40.0, CMS.INITBYDIM and CMS.INITBYPROB accept dimensions whose width times depth times sizeof(int64_t) overflows in src/core/cms.cc, allocating an undersized counter buffer while CMS.INCRBY and CMS.QUERY use the unbounded dimensions, which allows an unauthenticated remote client to corrupt or disclose adjacent heap memory and crash the server. This issue is fixed in version 1.40.0.

Weakness: CWE-190 (Integer Overflow or Wraparound)

## Which versions are affected by CVE-2026-62357?


## How do I fix CVE-2026-62357?

No fix has been published for CVE-2026-62357 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-62357 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-62357 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-62357 and fix it if it is affected.

What it is: CVE-2026-62357 is a high-severity vulnerability in dragonflydb dragonfly, published on 18 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-62357 exists.

Affected product: dragonflydb dragonfly. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-62357/ (Markdown: https://insights.sbomify.com/CVE-2026-62357/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-62357
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-62357
- OSV: https://osv.dev/vulnerability/CVE-2026-62357

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-62357/
Summaries are generated and may contain mistakes; the official description above is the record.