# CVE-2020-5753: Information disclosure in Signal Private Messenger

> Remote attackers can disclose the victim's DNS server and ring their phone via ICE Candidate handling flaws in Signal mobile apps.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 20 May 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-cqgm-mqmr-px3p

## What is CVE-2020-5753?

CVE-2020-5753 is a medium-severity vulnerability in Signal Private Messenger, published on 20 May 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Signal Private Messenger Android v4.59.0 and up and iOS v3.8.1.5 and up allows a remote non-contact to ring a victim's Signal phone and disclose currently used DNS server due to ICE Candidate handling before call is answered or declined.

Weakness: CWE-670 (Always-Incorrect Control Flow Implementation)

## Which versions are affected by CVE-2020-5753?

It affects 2 products.


Products: Signal Private Messenger, Signal Signal.

## How do I fix CVE-2020-5753?

No fix has been published for CVE-2020-5753 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-5753 being exploited?

There is no known exploitation of CVE-2020-5753 in the wild and no public exploit code.

## Other vulnerabilities in Signal Private Messenger

- [CVE-2019-17192](https://insights.sbomify.com/CVE-2019-17192/): Denial of service in n/a (critical 9.8)
- [CVE-2019-17191](https://insights.sbomify.com/CVE-2019-17191/): Security feature bypass in n/a (high 7.5)
- [CVE-2019-9970](https://insights.sbomify.com/CVE-2019-9970/): Other in n/a (medium 6.5)
- [CVE-2018-3988](https://insights.sbomify.com/CVE-2018-3988/): Information disclosure in Signal (low 3.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-5753 and fix it if it is affected.

What it is: CVE-2020-5753 is a medium-severity vulnerability in Signal Private Messenger, published on 20 May 2020. 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-2020-5753 in the wild and no public exploit code.

Affected product: Signal Private Messenger. 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-2020-5753/ (Markdown: https://insights.sbomify.com/CVE-2020-5753/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-5753
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-5753
- OSV: https://osv.dev/vulnerability/CVE-2020-5753

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-5753/
Summaries are generated and may contain mistakes; the official description above is the record.