Kamailio
CVE-2020-28361
MEDIUM
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V4 - API and Web Service HTTP request consistency
|
| Impact | CVSS score of 5.4 (MEDIUM). Attack characteristics: network attack vector, low complexity, low privileges required, no user interaction not required. Public proof-of-concept exploit code is available. |
| Exploit ScenarioDerived | A remote attacker could manipulate HTTP request interpretation between frontend and backend servers by sending crafted requests to the affected application. |
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Alert meAnalysisAI
Kamailio before 5.4.0, as used in Sip Express Router (SER) in Sippy Softswitch 4.5 through 5.2 and other products, allows a bypass of a header-removal protection mechanism via whitespace characters. Rated medium severity (CVSS 5.4), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
RemediationAI
No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Enforce strict HTTP parsing, normalize requests at proxy layer, use HTTP/2 end-to-end, reject ambiguous headers.
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Technical ContextAI · show details
This vulnerability is classified as HTTP Request/Response Smuggling (CWE-444), which allows attackers to manipulate HTTP request interpretation between frontend and backend servers. Kamailio before 5.4.0, as used in Sip Express Router (SER) in Sippy Softswitch 4.5 through 5.2 and other products, allows a bypass of a header-removal protection mechanism via whitespace characters. This occurs in the remove_hf function in the Kamailio textops module. Particular use of remove_hf in Sippy Softswitch may allow skilled attacker having a valid credential in the system to disrupt internal call start/duration accounting mechanisms leading potentially to a loss of revenue. Affected products include: Kamailio. Version information: before 5.4.0.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
DescriptionNVD
Kamailio before 5.4.0, as used in Sip Express Router (SER) in Sippy Softswitch 4.5 through 5.2 and other products, allows a bypass of a header-removal protection mechanism via whitespace characters. This occurs in the remove_hf function in the Kamailio textops module. Particular use of remove_hf in Sippy Softswitch may allow skilled attacker having a valid credential in the system to disrupt internal call start/duration accounting mechanisms leading potentially to a loss of revenue.
Threat Intelligence Overview
NVD
CVE.org
EPSS
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.
HTTP request smuggling exploits inconsistencies in how front-end and back-end servers parse HTTP message boundaries.
Affected Products (CPE)NVD
Heap-based buffer overflow in the encode_msg function in encode_msg.c in the SEAS module in Kamailio (formerly OpenSER a
In Kamailio before 5.0.7 and 5.1.x before 5.1.4, a crafted SIP message with an invalid Via header causes a segmentation
In Kamailio before 5.0.7 and 5.1.x before 5.1.4, a crafted SIP message with a double "To" header and an empty "To" tag c
Insecure Temporary file vulnerability in /tmp/kamailio_fifo in kamailio 4.0.1. Rated critical severity (CVSS 9.8), this
A Buffer Overflow issue was discovered in Kamailio before 4.4.7, 5.0.x before 5.0.6, and 5.1.x before 5.1.2. Rated criti
Heap-based buffer overflow in Kamailio's CDP (C Diameter Peer) module allows a remote party that can deliver a malformed
The kamcmd administrative utility and default configuration in kamailio before 4.3.0 use /tmp/kamailio_ctl. Rated high s
The kamailio build in kamailio before 4.2.0-2 process allows local users to gain privileges. Rated high severity (CVSS 7
Denial of service in Kamailio v6.1.1 and earlier allows an unauthenticated remote attacker to crash the SIP proxy by sen
Out-of-bounds memory access in Kamailio SIP server versions before 5.8.8, 6.0.6, and 6.1.1 enables unauthenticated remot
A heap/stack-adjacent buffer overflow in Kamailio's optional sipt module lets remote, unauthenticated attackers crash th
Out-of-bounds read in Kamailio's IMS AVP handler exposes telecom infrastructure to remote memory disclosure and potentia
GitHub PoC
Exploit-DB