Buffer Overflow in Kamailio (CVE-2026-39863)
Summary
Vulnerability in Kamailio (CVE-2026-39863). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 5.1.1 or later.
Original description
The description as published by the source.
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.
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-39863 has been found in Kamailio.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade Kamailio to 5.1.1 or later.
If unsure, ask your IT team or search "Kamailio CVE-2026-39863" on the vendor's site.
CVE-2026-39863 (Kamailio) — CWE-119 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 5.1.1 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-119) exists in Kamailio.
Check the vendor advisory for the affected versions of Kamailio.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
Update to 5.1.1.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'Kamailio' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'Kamailio' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
Kamailioを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade Kamailio to 5.1.1ステージング環境で 5.1.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Alpine Linux ALPINE-CVE-2026-39863 kamailio Fixed in: 5.4.5-r2
- Debian DEBIAN-CVE-2026-39863 kamailio
- Ubuntu UBUNTU-CVE-2026-39863 kamailio
References
- advisory github.com
- advisory github.com
- advisory nvd.nist.gov