# CVE-2021-27439: TencentOS-tiny Integer Overflow or Wraparound

> An integer overflow in TencentOS-tiny's memory allocator allows attackers to cause crashes or execute arbitrary code.

- **Severity:** High 7.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 3 May 2022
- **Updated:** 16 Apr 2025
- **Also known as:** GHSA-q338-m4f4-2mm6

## What is CVE-2021-27439?

CVE-2021-27439 is a high-severity vulnerability in TencentOS-tiny, published on 3 May 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

TencentOS-tiny version 3.1.0 is vulnerable to integer wrap-around in function 'tos_mmheap_alloc incorrect calculation of effective memory allocation size. This improper memory assignment can lead to arbitrary memory allocation, resulting in unexpected behavior such as a crash or a remote code injection/execution.

Weakness: CWE-190 (Integer Overflow or Wraparound)

## Which versions are affected by CVE-2021-27439?

It affects 1 product.


Products: Tencent Tencentos-Tiny.

## How do I fix CVE-2021-27439?

No fix has been published for CVE-2021-27439 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-27439 being exploited?

There is no known exploitation of CVE-2021-27439 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-27439 and fix it if it is affected.

What it is: CVE-2021-27439 is a high-severity vulnerability in TencentOS-tiny, published on 3 May 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-27439 in the wild and no public exploit code.

Affected product: TencentOS-tiny. 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-2021-27439/ (Markdown: https://insights.sbomify.com/CVE-2021-27439/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-27439
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-27439
- OSV: https://osv.dev/vulnerability/CVE-2021-27439

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-27439/
Summaries are generated and may contain mistakes; the official description above is the record.