CVE-2026-45537Public exploitNetwork attack vector

Routing manipulation via unchecked URI concatenation

Published Aug 4, 2026 · Updated Aug 4, 2026

Buffer overflow in OpenSIPS 3.4.0 through 3.6.5 and 4.0.0-beta allows remote attackers to alter SIP routing via a crafted URI. The construct_uri() function concatenates untrusted URI components with unchecked memcpy calls into a shared 1024-byte BSS buffer, overwriting adjacent global data including disable_503_translation. Reachability requires a routing script to pass attacker-controlled SIP fields into construct_uri(); one unauthenticated message can change 503 handling for subsequent traffic.

CVSS severity9.1
Critical
EPSS probability0.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer overflow in OpenSIPS 3.4.0 through 3.6.5 and 4.0.0-beta allows remote attackers to alter SIP routing via a crafted URI. The construct_uri() function concatenates untrusted URI components with unchecked memcpy calls into a shared 1024-byte BSS buffer, overwriting adjacent global data including disable_503_translation. Reachability requires a routing script to pass attacker-controlled SIP fields into construct_uri(); one unauthenticated message can change 503 handling for subsequent traffic.

The record

CVE
CVE-2026-45537
Published
Aug 4, 2026
Updated
Aug 4, 2026
Vendor
OpenSIPS
Product
OpenSIPS
Classifications
CWE-120, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 4, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 3.4.0, < 3.6.6
  2. Affected versionversion=>= 4.0.0-beta, < 4.0.0-rc1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

OpenSIPS · OpenSIPSversion=>= 3.4.0, < 3.6.6; version=>= 4.0.0-beta, < 4.0.0-rc1

Published CVSS scores

9.1GitHub CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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