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CVE Record

CVE-2018-20356: An invalid read of 8 bytes due to a use-after-free vulnerability in the mg_http_free_proto_data_cgi functio...

An invalid read of 8 bytes due to a use-after-free vulnerability in the mg_http_free_proto_data_cgi function call in mongoose.c in Cesanta Mongoose Embedded Web Server Library 6.13 and earlier allows a denial of service (application crash) or remote code execution.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2018-20356 is a memory safety bug in Cesanta Mongoose Embedded Web Server Library 6.13 and earlier. A remote interaction with CGI-related HTTP handling could crash an application and the CVE description says remote code execution is possible. The public record does not provide CVSS, named patches, or evidence of active exploitation.

Executive priority

Prioritize discovery and vendor follow-up for internet-facing or operationally critical embedded web services. The lack of CVSS and patch details limits precision, but the stated impact includes crashes and possible remote code execution.

Technical view

The issue is a use-after-free causing an invalid 8-byte read in mg_http_free_proto_data_cgi in mongoose.c. The affected component is Mongoose Embedded Web Server Library 6.13 and earlier. The CVE description lists denial of service through application crash and potential remote code execution, but supporting technical detail is limited to the CVE record and a fuzzing artifact reference.

Likely exposure

Exposure is most likely in applications, appliances, or embedded services that include Mongoose Embedded Web Server Library 6.13 or earlier and enable affected CGI/HTTP server functionality. The source bundle does not identify specific downstream products or CPEs.

Exploitation context

CISA KEV status is false in the supplied bundle. The public reference appears to be a fuzzing screenshot, not evidence of active exploitation. Treat exploit maturity as unclear, while recognizing that memory corruption in an embedded web server can be operationally significant.

Researcher notes

The main evidence is the CVE description and a fuzzing image reference. There are no supplied CWE mappings, CPEs, CVSS metrics, patch commits, or exploit-in-the-wild reports. Avoid assuming downstream affected products without product-specific confirmation.

Mitigation direction

  • Inventory software using Mongoose Embedded Web Server Library 6.13 or earlier.
  • Check Cesanta or product-vendor guidance for fixed versions or supported mitigations.
  • Prioritize systems exposing Mongoose HTTP services to untrusted networks.
  • Disable or restrict CGI-related functionality where vendor guidance supports doing so.
  • Use network controls to limit access to affected embedded web interfaces.

Validation and detection

  • Identify bundled or statically linked Mongoose versions in products and firmware.
  • Confirm whether CGI handling is compiled, enabled, or reachable.
  • Review crash telemetry for Mongoose HTTP server faults around CGI cleanup.
  • Check vendor advisories for each product embedding the library.
  • Verify exposed management or web interfaces are not internet-accessible.
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

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

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.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2018-20356 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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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.