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TI-2026-36744 Aliases CVE-2026-49840

FreeSWITCH: Pre-authentication heap buffer overflow in libesl `Content-Length` parsing

Priority MEDIUM 45CWE-122Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
None · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

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, esl_recv_event() parses Content-Length with atol() and passes the result straight to malloc(len + 1) with no sign or magnitude check. A malicious or man-in-the-middle ESL peer can send a frame with a negative Content-Length to corrupt the heap of, or crash, any process linked against libesl, before the client has authenticated to that peer. This issue has been patched in version 1.11.1.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.0031 23rd percentileScored 2026-11-07
Fix Fixed freeswitch (signalwire): 1.11.1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
signalwirefreeswitchbefore 1.11.11.11.1Patch availableCNA
  • freeswitch Vendorsignalwire Affected before 1.11.1 Fixed in 1.11.1 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:freeswitch:freeswitch:*:*:*:*:*:*:*:*before 1.11.1Vulnerablefreeswitch
  • cpe:2.3:a:freeswitch:freeswitch:*:*:*:*:*:*:*:* Versions before 1.11.1 Vulnerable ·freeswitch

Remediation

  • Fix · CNA freeswitch (signalwire) Fixed in 1.11.1

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-49840

References

Advisory 1

Other 1

  • TI-2023-08915 heap-over-flow in stun_parse_attribute in sofia-sip CVSS 3.1CRITICAL 9.8
  • TI-2022-13049 Heap-based Buffer Overflow and Out-of-bounds Write in Sofia-SIP CVSS 3.1CRITICAL 9.8
  • TI-2023-28097 FreeSWITCH susceptible to Denial of Service via DTLS Hello packets during call initiation CVSS 3.1HIGH 7.5
  • TI-2023-20909 Resource allocation without limits in signalwire freeswitch CVSS 3.1HIGH 7.5
  • TI-2023-20908 FreeSWITCH allows remote users to trigger out of bounds write by offering an ICE candidate with unknown component ID CVSS 3.1HIGH 7.5
  • TI-2023-15601 heap-over-flow and integer-overflow in sofia-sip CVSS 3.1HIGH 7.5
See all 44 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences