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CVE Record

CVE-2020-28361: Kamailio before 5.4.0, as used in Sip Express Router (SER) in Sippy Softswitch 4.5 through 5.2 and other pr...

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.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This flaw lets a logged-in, skilled attacker bypass a SIP header-removal protection in Kamailio/SER using whitespace handling. In Sippy Softswitch deployments, the cited impact is disruption of internal call start and duration accounting, which can translate into revenue loss.

Executive priority

Prioritize assessment if telephony revenue, billing, or wholesale routing depends on Sippy Softswitch or Kamailio/SER. The issue is not cited as actively exploited, but authenticated misuse could directly affect revenue accounting.

Technical view

CVE-2020-28361 affects Kamailio before 5.4.0, specifically remove_hf in the textops module. The issue is a header-removal protection bypass involving whitespace characters. The CVE description names Sippy Softswitch 4.5 through 5.2 as using SER in a way that may expose call-accounting logic.

Likely exposure

Most likely exposed environments run Kamailio before 5.4.0 or SER-derived components in Sippy Softswitch 4.5 through 5.2. The source bundle does not identify broader product inventory or internet-wide exposure.

Exploitation context

The supplied CVE text describes a skilled attacker with valid system credentials. CISA KEV is false, and the bundle provides no cited evidence of active exploitation. Packet Storm indicates public technical disclosure exists.

Researcher notes

Evidence is limited to the CVE description and linked public references. No CVSS, CWE, or detailed fixed Sippy release is present in the supplied bundle. Avoid assuming unauthenticated exposure or broader Kamailio impact beyond the described header-removal bypass.

Mitigation direction

  • Upgrade Kamailio/SER components to 5.4.0 or later where applicable.
  • Check Sippy Softswitch vendor guidance for affected 4.5 through 5.2 deployments.
  • Review configurations that depend on SIP header removal for accounting integrity.
  • Monitor call accounting anomalies and credential misuse indicators.

Validation and detection

  • Inventory Kamailio, SER, and Sippy Softswitch versions in voice infrastructure.
  • Confirm whether remove_hf textops logic is used in production SIP processing.
  • Check whether call start and duration accounting depends on removable headers.
  • Review logs for unusual authenticated SIP activity or accounting mismatches.
Prepared
Confidence
medium
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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ATT&CK lookup starting points

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description · low confidence lookup

Credential and access behavior lookup

The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

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cve · low confidence lookup

CVE-2020-28361 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
3Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.