# CVE-2020-36946: SyncBreeze 10.0.28 - 'login' Denial of Service

> Remote attackers can crash the SyncBreeze service by sending oversized payloads to the login endpoint, disrupting availability.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/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:** 27 Jan 2026
- **Updated:** 7 Apr 2026
- **Also known as:** GHSA-xmhr-f2x4-rvcv

## What is CVE-2020-36946?

CVE-2020-36946 is a high-severity denial of service vulnerability in Flexense Ltd. SyncBreeze, published on 27 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

SyncBreeze 10.0.28 contains a denial of service vulnerability in the login endpoint that allows remote attackers to crash the service. Attackers can send an oversized payload in the login request to overwhelm the application and potentially disrupt service availability.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2020-36946?

It affects 1 product.


Products: Flexense Syncbreeze.

## How do I fix CVE-2020-36946?

No fix has been published for CVE-2020-36946 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-36946 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2020-36946 exists.

## Other vulnerabilities in Flexense Ltd. SyncBreeze

- [CVE-2018-6537](https://insights.sbomify.com/CVE-2018-6537/): Memory corruption in n/a (critical 9.8)
- [CVE-2017-14980](https://insights.sbomify.com/CVE-2017-14980/): Memory corruption in n/a (critical 9.8)
- [CVE-2017-17996](https://insights.sbomify.com/CVE-2017-17996/): Memory corruption in n/a (high 8.8)
- [CVE-2020-37100](https://insights.sbomify.com/CVE-2020-37100/): Sync Breeze Enterprise 12.4.18 - Unquoted Service Path (high 8.5)
- [CVE-2017-17099](https://insights.sbomify.com/CVE-2017-17099/): Memory corruption in n/a (high 7.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-36946 and fix it if it is affected.

What it is: CVE-2020-36946 is a high-severity denial of service vulnerability in Flexense Ltd. SyncBreeze, published on 27 Jan 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-2020-36946 exists.

Affected product: Flexense Ltd. SyncBreeze. 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-2020-36946/ (Markdown: https://insights.sbomify.com/CVE-2020-36946/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-36946
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-36946
- OSV: https://osv.dev/vulnerability/CVE-2020-36946

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-36946/
Summaries are generated and may contain mistakes; the official description above is the record.