CVE-2023-28095Public exploitNetwork attack vector

Server crash via negative-length header copy

Published Mar 15, 2023 · Updated Feb 25, 2025

Denial of service in OpenSIPS before 3.1.7 and 3.2.0 through 3.2.3 crashes an isolated harness through duplicate To headers. The build_res_buf_from_sip_req function reuses the first To-tag pointer while processing a second To header, passes a negative length to append_str, and aborts under AddressSanitizer. The audit found no public function that reaches this code and could not reproduce the crash in a running server, so operational exposure remains unverified and the bounded impact is a service crash.

CVSS severity7.5
High
EPSS probability0.97%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in OpenSIPS before 3.1.7 and 3.2.0 through 3.2.3 crashes an isolated harness through duplicate To headers. The build_res_buf_from_sip_req function reuses the first To-tag pointer while processing a second To header, passes a negative length to append_str, and aborts under AddressSanitizer. The audit found no public function that reaches this code and could not reproduce the crash in a running server, so operational exposure remains unverified and the bounded impact is a service crash.

The record

CVE
CVE-2023-28095
Published
Mar 15, 2023
Updated
Feb 25, 2025
Vendor
OpenSIPS
Product
OpenSIPS
Classifications
CWE-20
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 15, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 25, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=< 3.1.7
  2. Affected versionversion=>= 3.2.0, < 3.2.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

OpenSIPS · OpenSIPSversion=< 3.1.7; version=>= 3.2.0, < 3.2.4

Published CVSS scores

7.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.9OpenSIPS security auditCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
4.7OpenSIPS security auditCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:U

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-20Improper Input Validation

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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