# CVE-2026-27710: NanaZip .NET Single-File Parser Integer Underflow Leads to Unbounded Allocation (DoS)

> A crafted archive file can cause an integer underflow leading to unbounded memory allocation and denial of service in NanaZip.

- **Severity:** Medium 5.1 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 25 Feb 2026
- **Updated:** 26 Feb 2026
- **Also known as:** GHSA-89qw-8p49-32wf

## What is CVE-2026-27710?

CVE-2026-27710 is a medium-severity vulnerability in M2Team NanaZip, published on 25 Feb 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

NanaZip is an open source file archive. Starting in version 5.0.1252.0 and prior to versions 6.0.1638.0 and 6.5.1638.0, a denial-of-service vulnerability exists in NanaZip’s `.NET Single File Application` parser. A crafted bundle can force an integer underflow in header-size calculation and trigger an unbounded memory allocation attempt during archive open. Versions 6.0.1638.0 and 6.5.1638.0 fix the issue.

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

## Which versions are affected by CVE-2026-27710?

It affects 1 product.


Products: M2team Nanazip.

## How do I fix CVE-2026-27710?

No fix has been published for CVE-2026-27710 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-27710 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-27710 exists.

## Other vulnerabilities in M2Team NanaZip

- [CVE-2026-26282](https://insights.sbomify.com/CVE-2026-26282/): NanaZip has DotNet Single file OOB Heap Read (medium 5.2)
- [CVE-2026-27709](https://insights.sbomify.com/CVE-2026-27709/): NanaZip .NET Single-File Manifest Parser Vulnerable to Out-of-Bounds Read via Unchecked RelativePathLength (medium 5.1)
- [CVE-2026-27711](https://insights.sbomify.com/CVE-2026-27711/): NanaZip UFS Archive Parser Memory Corruption via Unvalidated Directory Record Length (medium 5.1)
- [CVE-2026-27014](https://insights.sbomify.com/CVE-2026-27014/): NanZip has ROMFS Archive Infinite Loop / Stack Overflow (medium 5.1)
- [CVE-2026-27114](https://insights.sbomify.com/CVE-2026-27114/): NanaZip has ROMFS Archive Infinite Loop (medium 5.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-27710 and fix it if it is affected.

What it is: CVE-2026-27710 is a medium-severity vulnerability in M2Team NanaZip, published on 25 Feb 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-2026-27710 exists.

Affected product: M2Team NanaZip. 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-2026-27710/ (Markdown: https://insights.sbomify.com/CVE-2026-27710/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-27710
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-27710
- OSV: https://osv.dev/vulnerability/CVE-2026-27710

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-27710/
Summaries are generated and may contain mistakes; the official description above is the record.