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CVE-2026-116574

FreeSWITCH: Off-by-one heap write in core XML serialization of four-byte UTF-8 sequences

5.9 Medium

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, switch_xml_ampencode() reserved only ten bytes for the widest numeric character reference produced from a four-byte UTF-8 sequence, omitting space for the terminating NUL. When remote-supplied text was serialized at the exact buffer-growth boundary, the terminator wrote one byte beyond the heap allocation. Reachable surfaces include mod_xml_cdr, conference and formatted CDR XML, XML Event Socket output, and XML API output that serializes caller-controlled values. The fixed zero-byte write can abort the process or truncate an adjacent object, while remote code execution has not been demonstrated. This issue is fixed in version 1.11.2.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
Low
Availability
High

Exploit likelihood

0.38%Unchanged since Nov 6, 2026
90%50%10%1%

What each source reports

CVE List Score used 5.9

FreeSWITCH: Off-by-one heap write in core XML serialization of four-byte UTF-8 sequences

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, switch_xml_ampencode() reserved only ten bytes for the widest numeric character reference produced from a four-byte UTF-8 sequence, omitting space for the terminating NUL. When remote-supplied text was serialized at the exact buffer-growth boundary, the terminator wrote one byte beyond the heap allocation. Reachable surfaces include mod_xml_cdr, conference and formatted CDR XML, XML Event Socket output, and XML API output that serializes caller-controlled values. The fixed zero-byte write can abort the process or truncate an adjacent object, while remote code execution has not been demonstrated. This issue is fixed in version 1.11.2.

Record
CVE-2026-116574
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:H
Weakness
CWE-193, CWE-787
Updated
2026-11-05
EUVDEUVD-2026-117731 5.9

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, switch_xml_ampencode() reserved only ten bytes for the widest numeric character reference produced from a four-byte UTF-8 sequence, omitting space for the terminating NUL. When remote-supplied text was serialized at the exact buffer-growth boundary, the terminator wrote one byte beyond the heap allocation. Reachable surfaces include mod_xml_cdr, conference and formatted CDR XML, XML Event Socket output, and XML API output that serializes caller-controlled values. The fixed zero-byte write can abort the process or truncate an adjacent object, while remote code execution has not been demonstrated. This issue is fixed in version 1.11.2.

Record
EUVD-2026-117731
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:H
Updated
2026-11-05
NVD 5.9

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, switch_xml_ampencode() reserved only ten bytes for the widest numeric character reference produced from a four-byte UTF-8 sequence, omitting space for the terminating NUL. When remote-supplied text was serialized at the exact buffer-growth boundary, the terminator wrote one byte beyond the heap allocation. Reachable surfaces include mod_xml_cdr, conference and formatted CDR XML, XML Event Socket output, and XML API output that serializes caller-controlled values. The fixed zero-byte write can abort the process or truncate an adjacent object, while remote code execution has not been demonstrated. This issue is fixed in version 1.11.2.

Record
CVE-2026-116574
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:H
Weakness
CWE-193, CWE-787
Updated
2026-11-05
OSV 5.9

FreeSWITCH: Off-by-one heap write in core XML serialization of four-byte UTF-8 sequences

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, switch_xml_ampencode() reserved only ten bytes for the widest numeric character reference produced from a four-byte UTF-8 sequence, omitting space for the terminating NUL. When remote-supplied text was serialized at the exact buffer-growth boundary, the terminator wrote one byte beyond the heap allocation. Reachable surfaces include mod_xml_cdr, conference and formatted CDR XML, XML Event Socket output, and XML API output that serializes caller-controlled values. The fixed zero-byte write can abort the process or truncate an adjacent object, while remote code execution has not been demonstrated. This issue is fixed in version 1.11.2.

Record
CVE-2026-116574
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:H
Weakness
CWE-193, CWE-787
Updated
2026-11-07

Affected products

History

History
RecordedChangedSources
aliases, referencesNVD, OSV
first indexedCVE List, EUVD

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-116574 is a medium vulnerability (CVSS 5.9) in Signalwire Freeswitch, published November 5, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.38%, the 32nd percentile. No source names a fixed version.

References

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