How severe is CVE-2026-39863?

CVE-2026-39863 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-39863 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (37th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-39863?

CVE-2026-39863 primarily affects Kamailio. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-39863?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-39863 have an EU (EUVD) identifier?

Yes. CVE-2026-39863 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-20616.

When was CVE-2026-39863 published?

CVE-2026-39863 was published on 2026-04-08 and last updated on 2026-06-17.

CVE-2026-39863

CVE-2026-39863 is a high-severity vulnerability in Kamailio with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-119.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 0% (37th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-20616
Weakness: CWE-119
Affected product: Kamailio
Published: 2026-04-08
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2026-39863?: 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.
How severe is CVE-2026-39863?: CVE-2026-39863 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-39863 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (37th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-39863?: CVE-2026-39863 primarily affects Kamailio. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-39863?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-39863 have an EU (EUVD) identifier?: Yes. CVE-2026-39863 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-20616.
When was CVE-2026-39863 published?: CVE-2026-39863 was published on 2026-04-08 and last updated on 2026-06-17.

References

https://github.com/kamailio/kamailio/security/advisories/GHSA-2wj4-f825-2h2f

Affected products (2)

cpe:2.3:a:kamailio:kamailio:*:*:*:*:*:*:*:*
cpe:2.3:a:kamailio:kamailio:6.1.0:*:*:*:*:*:*:*

More vulnerabilities in Kamailio

CVE-2020-27507 — Critical (CVSS 9.8): The Kamailio SIP before 5.5.0 server mishandles INVITE requests with duplicated fields and overlength tag, leading to a…
CVE-2018-16657 — Critical (CVSS 9.8): In Kamailio before 5.0.7 and 5.1.x before 5.1.4, a crafted SIP message with an invalid Via header causes a segmentation…
CVE-2018-14767 — Critical (CVSS 9.8): In Kamailio before 5.0.7 and 5.1.x before 5.1.4, a crafted SIP message with a double "To" header and an empty "To" tag…
CVE-2018-8828 — Critical (CVSS 9.8): A Buffer Overflow issue was discovered in Kamailio before 4.4.7, 5.0.x before 5.0.6, and 5.1.x before 5.1.2. A…
CVE-2013-7426 — Critical (CVSS 9.8): Insecure Temporary file vulnerability in /tmp/kamailio_fifo in kamailio 4.0.1.
CVE-2016-2385 — Critical (CVSS 9.8): Heap-based buffer overflow in the encode_msg function in encode_msg.c in the SEAS module in Kamailio (formerly OpenSER…

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