# CVE-2026-116781: FreeSWITCH: Pre-authentication out-of-bounds writes in mod_xml_rpc WebSocket frame parsing

Status: published. Published: 2026-11-05. Updated: 2026-11-09.

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 1.11.2, ws_read_frame() unmasked a WebSocket payload by iterating wsh->datalen, which included frame headers, while indexing from the payload pointer. A masked frame filling the 64 KiB receive buffer could therefore XOR up to 14 bytes beyond the buffer, and the exact-capacity case also wrote a terminating NUL one byte out of bounds. The flaw is reachable before authentication when mod_xml_rpc and its opt-in WebSocket endpoint are enabled, while both features are disabled in the stock configuration. The writes remain within the same connection handle's adjacent outbound buffer, so neither a process crash nor cross-session disclosure has been demonstrated. This issue is fixed in version 1.11.2.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- signalwire / freeswitch: < 1.11.2 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- CVSS 3.1: 5.3 (medium); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N; source: CNA: GitHub_M

- CVSS 3.1: 5.3 (medium); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N; source: NVD: security-advisories@github.com

- CISA KEV: No listing in collected sources

- EPSS: 0.27% as of 2026-11-09; percentile 18.48%

- SSVC: exploitation none; automatable yes; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-193, CWE-787

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/signalwire/freeswitch/security/advisories/GHSA-4cg6-rvh2-cw74 (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/signalwire/freeswitch/commit/fb9f37b9c7869630ee52a3ae87399fbbf99ad74d (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/signalwire/freeswitch/releases/tag/v1.11.2 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/signalwire/freeswitch/commit/fb9f37b9c7869630ee52a3ae87399fbbf99ad74d (security-advisories@github.com)

- https://github.com/signalwire/freeswitch/releases/tag/v1.11.2 (security-advisories@github.com)

- https://github.com/signalwire/freeswitch/security/advisories/GHSA-4cg6-rvh2-cw74 (security-advisories@github.com)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-116781; retrieved 2026-11-09; source updated 2026-11-09

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-116781; retrieved 2026-11-10; source updated 2026-11-09

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-116781; retrieved 2026-11-09; source updated Not reported

Revision: 3c672f105406f9c4d3791a9ecae3808501efa81d4883e8df9f3227b47b520523

Canonical: https://y2.dev/cve/CVE-2026-116781

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