CVE-2026-45100

9.1 CRITICALpublic exploit available

Published 2026-08-04 · Updated 2026-08-05

AI risk analysis

Summary: The flaw is a buffer overflow in the {s.b64encode} string transformation in OpenSIPS, which can lead to corruption of adjacent buffers and potentially remote code execution.
Exploitability: Exploitation is moderately hard and depends on the deployment's routing configuration, requiring a large header value in a SIP message.
Blast radius: If exploited, the issue could lead to remote code execution and data corruption affecting SIP messages processed by the server.
Detection: No reliable host or network indicator is derivable from the published description.
Prioritized remediation: Upgrade to OpenSIPS 3.6.6 or 4.0.0-rc1 or later.

buffer-overflowsipsremote-code-execution

Analysis generated locally by qwen2.5:7b-instruct (no data left the box). AI-assisted — verify against primary sources before acting.

NVD description

OpenSIPS is a Session Initiation Protocol (SIP) server implementation. Versions 3.4.0-beta through 3.6.5 and 4.0.0-beta contain a buffer overflow in the {s.b64encode} string transformation. The size check for {s.b64encode} only verifies that the input fits within the 64 KB transformation buffer, but base64 encoding expands the data by roughly a third, so an input between about 49,153 and 65,535 bytes produces more output than the buffer can hold and overflows it by up to 21,844 bytes. Because these transformation buffers sit next to each other in memory and are reused for chained transformations, the overflow writes attacker-controlled data into the adjacent buffer and corrupts values used by later transformations processing the same SIP message. A remote attacker can trigger this by sending a SIP message with a large header value (roughly 50,000 bytes or more) when the routing script applies {s.b64encode} to attacker-controlled input, making exploitability dependent on the deployment's routing configuration. This issue has been fixed in versions 3.6.6 and 4.0.0-rc1.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

Weaknesses

CWE-120

Public exploit & PoC references

All references

Source data: NVD (nvd.nist.gov), public domain. Exploit-DB.ai adds local AI analysis for defensive use only.

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