What is CVE-2026-45537?

CVE-2026-45537 is a critical-severity vulnerability in Opensips, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 9.1/10. Published 2026-08-04.

How severe is CVE-2026-45537?

Critical severity. CVSS v3 base score is 9.1 out of 10.

Buffer overflow in Opensips

CVE-2026-45537

OpenSIPS is a Session Initiation Protocol (SIP) server implementation. In versions prior to 3.6.6 and 4.0.0-rc1, the construct_uri() function concatenates multiple URI components (protocol, username, domain, port, params) into a fixed 1024…

Vulnerability class: Buffer Overflow

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H.

Affected products

Opensips — versions >= 3.4.0, < 3.6.6, >= 4.0.0-beta, < 4.0.0-rc1

Weakness classification (CWE)

CWE-120 — Buffer Copy without Checking Size of Input (Classic Buffer Overflow)

References

security-advisories@github.com (x_refsource_CONFIRM)
security-advisories@github.com (x_refsource_MISC)
security-advisories@github.com (x_refsource_MISC)

Frequently asked questions

What is CVE-2026-45537?: CVE-2026-45537 is a critical-severity vulnerability in Opensips, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 9.1/10. Published 2026-08-04.
How severe is CVE-2026-45537?: Critical severity. CVSS v3 base score is 9.1 out of 10.