# CVE-2021-41105: FreeSWITCH susceptible to Denial of Service via invalid SRTP packets

> Remote attackers can terminate ongoing SRTP calls by flooding media ports with crafted packets, causing denial of service in FreeSWITCH.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Oct 2021
- **Updated:** 4 Aug 2024
- **Also known as:** ALPINE-CVE-2021-41105, GHSA-jh42-prph-gp36

## What is CVE-2021-41105?

CVE-2021-41105 is a high-severity denial of service vulnerability in signalwire freeswitch, published on 25 Oct 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

FreeSWITCH is a Software Defined Telecom Stack enabling the digital transformation from proprietary telecom switches to a software implementation that runs on any commodity hardware. When handling SRTP calls, FreeSWITCH prior to version 1.10.7 is susceptible to a DoS where calls can be terminated by remote attackers. This attack can be done continuously, thus denying encrypted calls during the attack. When a media port that is handling SRTP traffic is flooded with a specially crafted SRTP packet, the call is terminated leading to denial of service. This issue was reproduced when using the SDES key exchange mechanism in a SIP environment as well as when using the DTLS key exchange mechanism in a WebRTC environment. The call disconnection occurs due to line 6331 in the source file `switch_rtp.c`, which disconnects the call when the total number of SRTP errors reach a hard-coded threshold (100). By abusing this vulnerability, an attacker is able to disconnect any ongoing calls that are using SRTP. The attack does not require authentication or any special foothold in the caller's or the callee's network. This issue is patched in version 1.10.7.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2021-41105?

It affects 1 product.


Products: Freeswitch Freeswitch.

## How do I fix CVE-2021-41105?

Upgrade to a fixed version.

## Is CVE-2021-41105 being exploited?

There is no known exploitation of CVE-2021-41105 in the wild and no public exploit code.

## Other vulnerabilities in signalwire freeswitch

- [CVE-2026-49841](https://insights.sbomify.com/CVE-2026-49841/): FreeSWITCH: Pre-authentication heap buffer overflow in `mod_verto` HTTP POST body read (critical 9.8)
- [CVE-2019-19492](https://insights.sbomify.com/CVE-2019-19492/): Hardcoded credentials in n/a (critical 9.8)
- [CVE-2026-49840](https://insights.sbomify.com/CVE-2026-49840/): FreeSWITCH: Pre-authentication heap buffer overflow in libesl `Content-Length` parsing (critical 9.1)
- [CVE-2021-41145](https://insights.sbomify.com/CVE-2021-41145/): FreeSWITCH susceptible to Denial of Service via SIP flooding (high 8.6)
- [CVE-2026-45771](https://insights.sbomify.com/CVE-2026-45771/): Freeswitch Denial-of-Service in SIP PUBLISH Requests via XML Entity Expansion (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-41105 and fix it if it is affected.

What it is: CVE-2021-41105 is a high-severity denial of service vulnerability in signalwire freeswitch, published on 25 Oct 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-2021-41105 in the wild and no public exploit code.

Affected product: signalwire freeswitch. 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-2021-41105/ (Markdown: https://insights.sbomify.com/CVE-2021-41105/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-41105
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-41105
- OSV: https://osv.dev/vulnerability/CVE-2021-41105

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-41105/
Summaries are generated and may contain mistakes; the official description above is the record.