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CVE-2021-33898: In Invoice Ninja before 4.4.0, there is an unsafe call to unserialize() in app/Ninja/Repositories/AccountRe...

In Invoice Ninja before 4.4.0, there is an unsafe call to unserialize() in app/Ninja/Repositories/AccountRepository.php that may allow an attacker to deserialize arbitrary PHP classes. In certain contexts, this can result in remote code execution. The attacker's input must be hosted at http://www.geoplugin.net (cleartext HTTP), and thus a successful attack requires spoofing that site or obtaining control of it.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

Invoice Ninja before 4.4.0 could process untrusted data with PHP unserialize(), which can become remote code execution in some contexts. The known attack path is constrained because attacker-controlled input must appear to come from http://www.geoplugin.net, requiring spoofing, interception, or control of that site.

Executive priority

Treat this as a targeted upgrade and exposure review, not an emergency internet-wide incident. The impact can be severe, but the public sources describe difficult exploitation prerequisites and no confirmed active exploitation.

Technical view

The issue is an unsafe unserialize() call in app/Ninja/Repositories/AccountRepository.php. The CVE states arbitrary PHP class deserialization may be possible and can lead to remote code execution in certain contexts. Exploitation depends on controlling or spoofing cleartext HTTP content from www.geoplugin.net.

Likely exposure

Exposure is most likely in Invoice Ninja deployments running versions before 4.4.0, especially where outbound cleartext HTTP traffic or DNS for geoplugin.net could be intercepted or spoofed.

Exploitation context

The source bundle does not cite active exploitation, and KEV is false. The CVE describes a constrained prerequisite: attacker input must be hosted at http://www.geoplugin.net, requiring spoofing that site or obtaining control of it.

Researcher notes

Evidence is limited to the CVE description and referenced GitHub issue. No CVSS, CWE, exploit activity, or detailed patch notes are present in the supplied bundle. Avoid assuming broader affected products or easier exploitation than the stated geoplugin.net prerequisite.

Mitigation direction

  • Identify any Invoice Ninja deployments older than 4.4.0.
  • Upgrade affected Invoice Ninja instances to 4.4.0 or later where applicable.
  • Review vendor issue guidance before applying compensating controls.
  • Restrict or monitor unexpected cleartext HTTP access to geoplugin.net.
  • Ensure DNS and outbound web traffic use trusted network paths.

Validation and detection

  • Confirm Invoice Ninja version across production and backup environments.
  • Check whether AccountRepository.php contains unsafe unserialize() behavior.
  • Review outbound HTTP logs for requests to www.geoplugin.net.
  • Investigate DNS anomalies or proxy interception involving geoplugin.net.
  • Confirm remediation by retesting version and code path presence.
Prepared
Confidence
medium
Sources
3

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

Execution behavior lookup

The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

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CVE-2021-33898 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
2Source 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.