# CVE-2026-49843: FreeSWITCH: Pre-authentication session eviction via attacker-chosen `sessid` in `mod_verto`

> Unauthenticated attackers can evict legitimate VoIP sessions by colliding with known session IDs, causing service disruption.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 9 Jun 2026
- **Updated:** 10 Jun 2026
- **Also known as:** GHSA-9457-fxr9-x78m

## What is CVE-2026-49843?

CVE-2026-49843 is a medium-severity authentication bypass vulnerability in signalwire freeswitch, published on 9 Jun 2026. 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. Prior to version 1.11.1, mod_verto's JSON-RPC handler bound the connection to the client-supplied sessid on the first frame, before the authentication gate. Binding inserts the connection into the global session hash and, on a key collision, drops the prior occupant of that slot — sending it a verto.punt, detaching its calls, and closing its socket. An unauthenticated network attacker who knows a target session UUID could therefore evict the legitimate client. This issue has been patched in version 1.11.1.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2026-49843?

It affects 1 product.


Products: Freeswitch Freeswitch.

## How do I fix CVE-2026-49843?

No fix has been published for CVE-2026-49843 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-49843 being exploited?

There is no known exploitation of CVE-2026-49843 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-2026-49843 and fix it if it is affected.

What it is: CVE-2026-49843 is a medium-severity authentication bypass vulnerability in signalwire freeswitch, published on 9 Jun 2026. 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-2026-49843 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-2026-49843/ (Markdown: https://insights.sbomify.com/CVE-2026-49843/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-49843
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-49843
- OSV: https://osv.dev/vulnerability/CVE-2026-49843

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-49843/
Summaries are generated and may contain mistakes; the official description above is the record.