Targets IP Multimedia Subsystem, a core telecom infrastructure. Remote auth bypass (CVSS 9.8) can disrupt carrier signaling and subscriber services at scale.
CVE-2026-55366
Auth bypass in IP Multimedia Subsystem enabling remote privilege escalation
Is CVE-2026-55366 being exploited?
Not confirmed. CVE-2026-55366 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked.
How severe is CVE-2026-55366?
CVE-2026-55366 is rated Critical with a CVSS score of 9.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-55366?
Yes. A fix has been recorded for CVE-2026-55366. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-55366 affect?
CVE-2026-55366 affects IP Multimedia Subsystem (IMS), P-CSCF, S-CSCF, I-CSCF, and 3 further products or versions. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-55366?
Apply vendor security updates immediately; isolate IMS interfaces and monitor signaling logs.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote authentication bypass allows attackers to escalate privileges in IMS, control signaling, manipulate subscriber sessions, and disrupt telecom services.
Immediate action required
- affectedAndroid kernel
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.