Bug 2567760 (CVE-2026-116571)

Summary: CVE-2026-116571 freeswitch: FreeSWITCH: Denial of Service via stack buffer overflow in mod_rtmp
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in FreeSWITCH. When bridging an H.264 video call to a Real-Time Messaging Protocol (RTMP) endpoint, the mod_rtmp module copies incoming video stream parameters into a fixed-size stack buffer without verifying their size. A remote attacker can exploit this issue by sending oversized parameter sets to trigger a stack-based buffer overflow, causing a Denial of Service (DoS) by crashing the service and terminating active calls.
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Description OSIDB Bzimport 2026-11-05 22:24:00 UTC 
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, rtmp_rtp2rtmpH264() built an AVC decoder configuration record in a fixed stack buffer by copying wire-derived SPS and PPS values without checking that their sizes and framing fit. An established H.264 call bridged toward an RTMP endpoint could supply oversized SPS and PPS parameter sets and overrun the function's stack frame. The flaw affects only deployments that build and load mod_rtmp and bridge RTP media into an RTMP leg; the module is disabled in the stock build and configuration. The corruption can abort FreeSWITCH and terminate every active call, and builds without stack protection receive a limited stack-write primitive, although code execution has not been demonstrated. This issue is fixed in version 1.11.2.