# CVE-2023-53873: SyncBreeze 15.2.24 Denial of Service via Login Endpoint Overflow

> Attackers can crash the SyncBreeze service by sending oversized password parameters 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:** 15 Dec 2025
- **Updated:** 7 Apr 2026
- **Also known as:** GHSA-h7mp-qf49-hgph

## What is CVE-2023-53873?

CVE-2023-53873 is a high-severity denial of service vulnerability in SyncBreeze, published on 15 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

SyncBreeze 15.2.24 contains a denial of service vulnerability in the login authentication mechanism that allows attackers to crash the service. Attackers can send an oversized password parameter with repeated 'password=' values to overwhelm the login endpoint and potentially disrupt service availability.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2023-53873?


## How do I fix CVE-2023-53873?

No fix has been published for CVE-2023-53873 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-53873 being exploited?

There is no known exploitation of CVE-2023-53873 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-53873 and fix it if it is affected.

What it is: CVE-2023-53873 is a high-severity denial of service vulnerability in SyncBreeze, published on 15 Dec 2025. 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-2023-53873 in the wild and no public exploit code.

Affected product: 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-2023-53873/ (Markdown: https://insights.sbomify.com/CVE-2023-53873/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-53873
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-53873
- OSV: https://osv.dev/vulnerability/CVE-2023-53873

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-53873/
Summaries are generated and may contain mistakes; the official description above is the record.