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CVE Record

CVE-2018-20355: An invalid write of 8 bytes due to a use-after-free vulnerability in the mg_http_free_proto_data_cgi functi...

An invalid write 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-2018-20355 affects Cesanta Mongoose Embedded Web Server Library 6.13 and earlier. The reported flaw can cause an application crash and may allow remote code execution. The public bundle does not provide CVSS scoring, confirmed exploitation, or vendor remediation details.

Executive priority

Treat as a high-priority exposure discovery item for embedded web assets, especially externally reachable systems. Urgency is moderated by missing public evidence of active exploitation and absent remediation detail in the provided sources.

Technical view

The vulnerability is described as an 8-byte invalid write caused by use-after-free in mg_http_free_proto_data_cgi in mongoose.c. The stated impacts are denial of service through application crash or remote code execution. Evidence is limited to CVE metadata and a fuzzing-related GitHub reference.

Likely exposure

Exposure is most likely in products, firmware, or internal applications embedding Cesanta Mongoose Embedded Web Server Library 6.13 or earlier. The CVE record does not enumerate downstream vendors, product names, package identifiers, or CPEs.

Exploitation context

The provided sources do not state active exploitation, and the CVE is not marked as CISA KEV. The reference appears to be fuzzing evidence, not proof of exploitation in the wild.

Researcher notes

The public record is sparse: no CVSS vector, CWE, CPE list, patch reference, or exploit-in-the-wild citation is provided. Analysis should focus on version confirmation, embedded library provenance, and vendor-specific remediation tracking.

Mitigation direction

  • Inventory applications and devices embedding Mongoose 6.13 or earlier.
  • Check Cesanta and downstream vendor guidance for fixed versions or firmware updates.
  • Prioritize internet-facing embedded web interfaces for review.
  • Restrict access to affected web services where business operations allow.
  • Assess CGI-related functionality under vendor-supported configuration options.

Validation and detection

  • Confirm the embedded Mongoose version in source, binaries, firmware, or SBOMs.
  • Identify whether affected systems expose Mongoose-backed HTTP services.
  • Review vendor advisories for product-specific affected status.
  • Check crash reports for failures involving mg_http_free_proto_data_cgi.
  • Document compensating controls for exposed affected services.
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

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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 · low confidence lookup

CVE-2018-20355 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.