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CVE Record

CVE-2020-7765: Prototype Pollution

This affects the package @firebase/util before 0.3.4. This vulnerability relates to the deepExtend function within the DeepCopy.ts file. Depending on if user input is provided, an attacker can overwrite and pollute the object prototype of a program.

MediumCVSS 5.6Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2020-7765 is a medium-severity issue in @firebase/util before 0.3.4. A flawed deep copy helper can let attacker-controlled input change shared JavaScript object prototypes. Business impact is application-specific, but can include unexpected data changes, information exposure, or crashes where vulnerable dependency paths process untrusted objects.

Executive priority

Treat this as routine but real dependency risk. Prioritize remediation for internet-facing applications using Firebase packages, especially where external JSON or request bodies are processed. It does not currently justify emergency response based on the provided evidence.

Technical view

The vulnerability is prototype pollution in the deepExtend function within DeepCopy.ts. If user input reaches that function, an attacker may pollute Object prototype state. The CVSS 3.1 score is 5.6 with high attack complexity, no privileges, no user interaction, and low confidentiality, integrity, and availability impact.

Likely exposure

Exposure is most likely in JavaScript applications or builds with direct or transitive @firebase/util versions before 0.3.4, especially where untrusted objects are processed through Firebase utility deep-copy behavior.

Exploitation context

The provided sources do not show CISA KEV listing or active exploitation. The CVSS vector indicates network reachability without privileges or user interaction, but high attack complexity. Real-world exploitability depends on application-specific data flow into deepExtend.

Researcher notes

The key research question is reachability: whether attacker-controlled object keys can reach deepExtend in the vulnerable package version. Avoid assuming impact without confirming that path. The public references identify the vulnerable function and upstream fix, but the provided bundle does not include exploit details.

Mitigation direction

  • Upgrade @firebase/util to 0.3.4 or later.
  • Refresh lockfiles so transitive Firebase dependencies resolve to fixed versions.
  • Check Firebase JS SDK guidance and the referenced fix before deployment.
  • Reduce paths where untrusted object keys reach deep-copy utilities.

Validation and detection

  • Inspect package-lock, yarn.lock, or pnpm-lock for @firebase/util below 0.3.4.
  • Run dependency scanning against production build manifests.
  • Review application data flow for untrusted objects entering Firebase utility copy paths.
  • Confirm deployed artifacts use the updated dependency, not only source manifests.
Prepared
Confidence
high
Sources
5

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.

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CVE-2020-7765 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
5.6 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P/RL:O/RC:C

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.

1CVSS vectors
0Timeline events
0ADP providers
4Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
5.6CVSS 3.1MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P/RL:O/RC:C2.23.4Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

5.6Medium
CVSS 3.1 vector shape for CVE-2020-7765Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P/RL:O/RC:C

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/a@firebase/utilunspecifiedListed
Weakness

CWE details

No CWE listed

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