# CVE-2026-111137: libsmi through 0.5.0 Out-of-Bounds Write via smiValueAsString OCTET STRING DEFVAL

> Attackers can cause out-of-bounds writes and crashes in libsmi consumers by supplying crafted MIB files with large OCTET STRING values.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 15 Oct 2026
- **Updated:** 16 Oct 2026
- **Also known as:** AZL-108296, DEBIAN-CVE-2026-111137, ECHO-0f04-0e7e-a4bf, GHSA-xxf8-vfhv-w73c, UBUNTU-CVE-2026-111137

## What is CVE-2026-111137?

CVE-2026-111137 is a medium-severity memory corruption vulnerability in amartin755 libsmi, published on 15 Oct 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

libsmi through 0.5.0 contains an out-of-bounds write vulnerability in smiValueAsString() in lib/smi.c that allows attackers to overflow a fixed 1024-byte static buffer through hex rendering of OCTET STRING values. Attackers can supply a crafted MIB with an OCTET STRING DEFVAL of 512 or more octets and a leading 0x00 byte to corrupt adjacent library globals and crash smidump or other consumers.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-111137?


## How do I fix CVE-2026-111137?

No fix has been published for CVE-2026-111137 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-111137 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-111137 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-111137 and fix it if it is affected.

What it is: CVE-2026-111137 is a medium-severity memory corruption vulnerability in amartin755 libsmi, published on 15 Oct 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-111137 exists.

Affected product: amartin755 libsmi. 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-2026-111137/ (Markdown: https://insights.sbomify.com/CVE-2026-111137/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-111137
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-111137
- OSV: https://osv.dev/vulnerability/CVE-2026-111137

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-111137/
Summaries are generated and may contain mistakes; the official description above is the record.