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Kamailio CVE-2026-39863

| EUVD-2026-20616 HIGH
Buffer Overflow (CWE-119)
2026-04-08 security-advisories@github.com
Buffer Overflow Denial Of Service Kamailio
7.5
CVSS 3.1 · GitHub Advisory
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Severity by source

GitHub Advisory PRIMARY
7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

6
Analysis Updated
Apr 16, 2026 - 06:01 EUVD-patch-fix
executive_summary
Re-analysis Queued
Apr 16, 2026 - 05:29 backfill_euvd_patch
patch_released
Patch available
Apr 16, 2026 - 05:29 EUVD
5.8.8,6.1.1,6.0.6
EUVD ID Assigned
Apr 08, 2026 - 20:23 euvd
EUVD-2026-20616
Analysis Generated
Apr 08, 2026 - 20:23 vuln.today
CVE Published
Apr 08, 2026 - 20:16 nvd
HIGH 7.5

DescriptionGitHub Advisory

Kamailio is an open source implementation of a SIP Signaling Server. Prior to 6.1.1, 6.0.6, and 5.8.8, an out-of-bounds access in the core of Kamailio (formerly OpenSER and SER) allows remote attackers to cause a denial of service (process crash) via a specially crafted data packet sent over TCP. The issue impacts Kamailio instances having TCP or TLS listeners. This vulnerability is fixed in 5.1.1, 6.0.6, and 5.8.8.

AnalysisAI

Out-of-bounds memory access in Kamailio SIP server versions before 5.8.8, 6.0.6, and 6.1.1 enables unauthenticated remote attackers to crash server processes via malformed TCP packets. Affects deployments with TCP or TLS listeners enabled. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Craft malformed SIP packet
Exploit
Send over TCP to Kamailio listener
Execution
Trigger out-of-bounds memory access
Impact
Cause process crash
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Vulnerability AssessmentAI

Exploitation Remote unauthenticated attacker can exploit Kamailio versions prior to 5.8.8, 6.0.6, or 6.1.1 by sending a specially crafted data packet over TCP. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment CVSS 7.5 reflects high-severity DoS against unauthenticated TCP/TLS endpoints. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario Attacker sends crafted TCP packet to Kamailio SIP port (unauthenticated, network-accessible). Malformed data triggers out-of-bounds memory access in core packet handler, crashing the process. …
Remediation Vendor-released patches: upgrade to Kamailio 5.8.8, 6.0.6, or 6.1.1 depending on deployment branch. … Detailed patch versions, workarounds, and compensating controls in full report.
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Recommended ActionAI

Within 24 hours: identify all Kamailio deployments and document current versions (pre-5.8.8, pre-6.0.6, pre-6.1.1). …

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CVE-2026-39863 vulnerability details – vuln.today
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