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Review reviewHigh

CVE-2026-39863

kamailio

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.

CVSS
7.5
EPSS
0.46%
37.8% percentile
CISA KEV
Not listed
Published
2026.04.09
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability0.46%
Technical severityCVSS 7.5

Vulnerability overview

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.

Affected product and versions

Product
kamailio
Affected versions
>= < 5.8.8, >= >= 6.0.0, < 6.0.6, >= >= 6.1.0, < 6.1.1, < 5.8.8, >= 6.0.0 < 6.0.6, 6.1.0
Fixed versions
5.8.8, 6.0.6

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that kamailio and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE
CWE-119