# CVE-2021-27647: Memory corruption in Synology DiskStation Manager (DSM)

> Remote attackers can execute arbitrary code on Synology NAS devices via crafted web requests exploiting an out-of-bounds read in the iSCSI snapshot communication core.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 Mar 2021
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-vwc7-rhxw-hppq

## What is CVE-2021-27647?

CVE-2021-27647 is a critical memory corruption vulnerability in Synology Diskstation Manager, published on 12 Mar 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Out-of-bounds Read vulnerability in iscsi_snapshot_comm_core in Synology DiskStation Manager (DSM) before 6.2.3-25426-3 allows remote attackers to execute arbitrary code via crafted web requests.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2021-27647?

It affects 1 product.


Products: Synology Diskstation Manager.

## How do I fix CVE-2021-27647?

No fix has been published for CVE-2021-27647 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-27647 being exploited?

There is no known exploitation of CVE-2021-27647 in the wild and no public exploit code.

## Other vulnerabilities in Synology Diskstation Manager

- [CVE-2022-27624](https://insights.sbomify.com/CVE-2022-27624/): Memory corruption in DiskStation Manager (DSM) (critical 10.0)
- [CVE-2022-27625](https://insights.sbomify.com/CVE-2022-27625/): Memory corruption in DiskStation Manager (DSM) (critical 10.0)
- [CVE-2022-27626](https://insights.sbomify.com/CVE-2022-27626/): Race condition in DiskStation Manager (DSM) (critical 10.0)
- [CVE-2013-6955](https://insights.sbomify.com/CVE-2013-6955/): Path traversal in n/a (critical 10.0)
- [CVE-2022-22687](https://insights.sbomify.com/CVE-2022-22687/): Memory corruption in DiskStation Manager (DSM) (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-27647 and fix it if it is affected.

What it is: CVE-2021-27647 is a critical memory corruption vulnerability in Synology Diskstation Manager, published on 12 Mar 2021. 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-2021-27647 in the wild and no public exploit code.

Affected product: Synology Diskstation Manager. 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-2021-27647/ (Markdown: https://insights.sbomify.com/CVE-2021-27647/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-27647
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-27647
- OSV: https://osv.dev/vulnerability/CVE-2021-27647

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-27647/
Summaries are generated and may contain mistakes; the official description above is the record.