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PatchSiren cyber security CVE debrief

CVE-2026-49841 signalwire CVE debrief

CVE-2026-49841 is a critical heap overflow vulnerability in FreeSWITCH, a Software Defined Telecom Stack. The vulnerability exists in the mod_verto HTTP request handler, where a fixed 2 MiB buffer is allocated for a POST application/x-www-form-urlencoded body, but the Content-Length is accepted up to just under 10 MiB. This allows for an attacker-controlled heap overflow of up to ~8 MiB before the HTTP basic-auth check runs. The issue has been patched in version 1.11.1.

Vendor
signalwire
Product
freeswitch
CVSS
CRITICAL 9.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-09
Original CVE updated
2026-06-10
Advisory published
2026-06-09
Advisory updated
2026-06-10

Who should care

Users of FreeSWITCH versions prior to 1.11.1 should upgrade to 1.11.1 to mitigate this vulnerability.

Technical summary

The mod_verto HTTP request handler in FreeSWITCH allocates a fixed 2 MiB buffer for a POST application/x-www-form-urlencoded body but accepts Content-Length up to just under 10 MiB. The body-read loop is bounded by Content-Length rather than the buffer size, producing an attacker-controlled heap overflow of up to ~8 MiB -- before the HTTP basic-auth check runs.

Defensive priority

high

Recommended defensive actions

  • Upgrade to FreeSWITCH version 1.11.1 or later.
  • Refer to [ref-4](https://github.com/signalwire/freeswitch/releases/tag/v1.11.1) for release notes.
  • Refer to [ref-5](https://github.com/signalwire/freeswitch/security/advisories/GHSA-wfrq-qvg2-f88f) for additional information.

Evidence notes

The CVE-2026-49841 record and NVD detail can be found at [cve-org](https://www.cve.org/CVERecord?id=CVE-2026-49841) and [nvd](https://nvd.nist.gov/vuln/detail/CVE-2026-49841), respectively.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-49841 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-49841

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-49841 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-49841

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.