# CVE-2026-23748: Golioth Firmware SDK < 0.22.0 LightDB State Out-of-Bounds Read

> A size_t underflow in LightDB State parsing allows a malicious server to trigger an out-of-bounds read, crashing IoT devices.

- **Severity:** Medium 6.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/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:** 26 Feb 2026
- **Updated:** 14 Jul 2026
- **Also known as:** GHSA-h52p-5g3g-rxjm

## What is CVE-2026-23748?

CVE-2026-23748 is a medium-severity vulnerability in Golioth Firmware SDK, published on 26 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Golioth Firmware SDK version 0.10.0 prior to 0.22.0, fixed in commit d7f55b38, contain an out-of-bounds read in LightDB State string parsing. When processing a string payload, a payload_size value less than 2 can cause a size_t underflow when computing the number of bytes to copy (nbytes). The subsequent memcpy() reads past the end of the network buffer, which can crash the device. The condition is reachable from on_payload, and golioth_payload_is_null() does not block payload_size==1. A malicious server or MITM can trigger a denial of service.

Weakness: CWE-191 (Integer Underflow (Wrap or Wraparound))

## Which versions are affected by CVE-2026-23748?


## How do I fix CVE-2026-23748?

No fix has been published for CVE-2026-23748 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-23748 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-23748 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-23748 and fix it if it is affected.

What it is: CVE-2026-23748 is a medium-severity vulnerability in Golioth Firmware SDK, published on 26 Feb 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-2026-23748 exists.

Affected product: Golioth Firmware SDK. 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-2026-23748/ (Markdown: https://insights.sbomify.com/CVE-2026-23748/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23748
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23748
- OSV: https://osv.dev/vulnerability/CVE-2026-23748

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23748/
Summaries are generated and may contain mistakes; the official description above is the record.