CVE-2026-49840

CRITICALPre-NVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.1 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 77% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
9.1
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 9.1Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
9.1
EG Score
9.1(medium)
EPSS
22.8%
KEV
Not listed

Published

June 9, 2026

Last Modified

June 10, 2026

Advisory Details (2)

Auto-updated Jun 9, 2026
Patch available. Sources: github, github_release.
github_release Patch Available

FreeSWITCH v1.11.1 Release

Patch available: signalwire/freeswitch v1.11.1

https://github.com/signalwire/freeswitch/releases/tag/v1.11.1
github Patch Available

Pre-authentication heap buffer overflow in libesl `Content-Length` parsing. · Advisory · signalwire/freeswitch · GitHub

https://github.com/signalwire/freeswitch/security/advisories/GHSA-g597-9fgg-ghg9

Weakness Classification(4)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 26× in last 7d / 177× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 194 total refreshes for this CVE.

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Frequently asked(5)

What is CVE-2026-49840?
CVE-2026-49840 is a critical vulnerability published on June 9, 2026. 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, eslrecvevent() parses Content-Length with atol() and passes the result straight to…
When was CVE-2026-49840 disclosed?
CVE-2026-49840 was first published in the National Vulnerability Database on June 9, 2026, with the most recent update on June 10, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-49840 actively exploited?
CVE-2026-49840 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 22.8% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-49840?
CVE-2026-49840 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2026-49840?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-49840, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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