OpenSIPS: Global Buffer Overflow in construct_uri

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-45537
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-04 23:16:51 UTC
Updated2026-08-05 18:17:11 UTC
DescriptionOpenSIPS 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-byte global BSS buffer without any bounds checking. When a routing script calls construct_uri() with an attacker-controlled username, a combined component length exceeding 1024 bytes overflows the buffer, corrupting adjacent global data with attacker-controlled content. The overflow reaches disable_503_translation, a global flag controlling SIP 503 response handling, allowing an attacker to deterministically set the flag via the URI username and alter the server's routing behavior for subsequent messages. Because the same buffer is shared with contact_builder(), the overflow also corrupts that function's data, and without a memory sanitizer the adjacent globals are silently overwritten on every request containing a long username. This issue has been fixed in versions 3.6.6 and 4.0.0-rc1.

Risk And Classification

Primary CVSS: v3.1 9.1 CRITICAL from [email protected]

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

Problem Types: CWE-120 | CWE-120 CWE-120: Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
3.1CNADECLARED9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
High

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA OpenSIPS Opensips affected >= 3.4.0, < 3.6.6 Not specified
CNA OpenSIPS Opensips affected >= 4.0.0-beta, < 4.0.0-rc1 Not specified

References

ReferenceSourceLinkTags
github.com/OpenSIPS/opensips/commit/4d23613b65579b073784a07a65d3bf52443a... [email protected] github.com
github.com/OpenSIPS/opensips/commit/5f103effaf5f372cccffe0b138f16998eba1... [email protected] github.com
github.com/OpenSIPS/opensips/security/advisories/GHSA-v7h4-fwrc-c66v 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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