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  4. CVE 2026 45538 opensips stack buffer overflow in siptojson
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Back to active CVEs
Critical · CVSS 9.8CVE-2026-45538

OpenSIPS: Stack Buffer Overflow in sip_to_json() Header Name CopyCVE-2026-45538

Answer in brief

CVE-2026-45538 records a Critical severity (CVSS 9.8) vulnerability in OpenSIPS: Stack Buffer Overflow in sip_to_json() Header Name Copy. The current sources do not mark it as known exploited. The current feed maps OpenSIPS/opensips (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 4, 2026Updated Sep 8, 2026Source checked Nov 3, 2026First seen by HOL Aug 4, 2026Material review Sep 8, 2026
Upstream Advisory

Key facts

Risk
Critical · CVSS 9.8
Exploitation
Not marked as known exploited
Affected software
1 mapped package or product
Fix availability
Available

Why this deserves its current priority

CVSS is 9.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps OpenSIPS/opensips (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
PackageAffected rangeFixed version
OpenSIPS/opensipsgeneric<=4.0.0= 4.0.0

Recommended response

  1. 1Check inventory. Check lockfiles and deployed manifests for OpenSIPS/opensips.
  2. 2Review the reported fix. Update OpenSIPS/opensips to = 4.0.0 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

  1. Published upstream

    Aug 4, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  2. Source modified

    Sep 8, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  3. First seen by HOL

    Aug 4, 2026

Sources and claim methodology

  • GitHub security advisorygithub.com
Upstream source description

OpenSIPS is a Session Initiation Protocol (SIP) server implementation. In versions 4.0.0 and prior, processing a SIP message with a header name longer than 255 bytes causes a stack buffer overflow when sip_to_json() is called in the routing script. Function sip_to_json() (modules/sipmsgops/sipmsgops.c) copies SIP header names into a fixed 255-byte stack buffer without bounds checking, performing a memcpy of the full header-name length even though the SIP parser imposes no such limit (a header name can be roughly 65000 bytes). As a result, when a routing script calls sip_to_json(), a SIP message with a header name longer than 255 bytes triggers a stack buffer overflow in which both the length and content of the overwrite are attacker-controlled, corrupting the saved frame pointer and return address. A single unauthenticated UDP packet to the SIP port (5060) can crash the process or, on builds without stack protections, hijack the return address to achieve remote code execution. This affects deployments whose routing script invokes sip_to_json(). This issue was not fixed at the time of publication.

Quoted source text, attributed separately from HOL analysis.

Related CVEs

  • psqlODBC stack buffer overflow copying ctid and oid values for updatable cursorsAlso CWE-121
  • PyMuPDF 1.25.3 before 2.0 Stack Buffer Overflow via add_freetext_annot() CalloutAlso CWE-121
  • ReadyMedia 1.3.0 - 1.3.3 Stack Buffer Overflow via DFF ParserAlso CWE-121

Record context

Vulnerability class
Tool Poisoning
EPSS
Not reported
CWE IDs
CWE-121
Source
CVE List V5
Source checked
Nov 3, 2026
References
1 linked source
Open source record