CVE-2026-45100
Remote buffer overflow in OpenSIPS {s.b64encode} enabling potential remote code execution.
Is CVE-2026-45100 being exploited?
Not confirmed. CVE-2026-45100 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. EPSS currently estimates a 0.67% probability of exploitation in the next 30 days.
How severe is CVE-2026-45100?
CVE-2026-45100 is rated Critical with a CVSS score of 9.1. 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-2026-45100?
Yes. A fix has been recorded for CVE-2026-45100. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-45100 affect?
CVE-2026-45100 affects OpenSIPS 3.4.0-beta - 3.6.5, OpenSIPS 4.0.0-beta. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-45100?
Upgrade to OpenSIPS 3.6.6 or 4.0.0-rc1; block/limit oversized SIP headers if patch delayed.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote buffer overflow via {s.b64encode} with a large (~50KB+) SIP header can crash OpenSIPS or enable remote code execution by corrupting adjacent buffers.
Immediate action required
- affected>= 3.4.0-beta and < 3.6.6
- affected>= 4.0.0-beta and < 4.0.0-rc1
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.