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CVE Record

CVE-2020-28501: Regular Expression Denial of Service (ReDoS)

This affects the package es6-crawler-detect before 3.1.3. No limitation of user agent string length supplied to regex operators.

MediumCVSS 5.3Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

A vulnerable es6-crawler-detect dependency can spend excessive CPU time processing unusually long User-Agent strings. Attackers do not need accounts or user interaction if the application passes request headers into this library. The expected business impact is reduced availability, not data theft or data modification.

Executive priority

Treat this as a moderate availability risk. Prioritize remediation for public-facing services and high-traffic APIs using the affected package. It is less urgent than vulnerabilities enabling code execution or data compromise, but easy network reachability can still create operational disruption.

Technical view

CVE-2020-28501 is a ReDoS issue in es6-crawler-detect before 3.1.3. The CVSS 3.1 vector is AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L, score 5.3. The source states the package did not limit User-Agent string length before applying regular expressions.

Likely exposure

Exposure is most likely in JavaScript applications that depend on es6-crawler-detect before 3.1.3 and evaluate externally supplied User-Agent headers. Public source data does not provide CPEs or downstream product mappings.

Exploitation context

The CVE record is not marked KEV, and the supplied sources do not cite active exploitation. The weakness is network reachable when untrusted User-Agent input reaches the vulnerable regex logic, with availability as the affected security property.

Researcher notes

Evidence is narrow but consistent: affected package, vulnerable version boundary, and ReDoS cause are identified. The bundle does not include CWE IDs, CPEs, exploit proof, KEV listing, or downstream product impact. Validate actual exploitability through code path review, not package presence alone.

Mitigation direction

  • Upgrade es6-crawler-detect to version 3.1.3 or later.
  • Confirm vendor advisory details before applying any compensating control.
  • Limit accepted User-Agent header length at application or edge layers.
  • Regenerate lockfiles and redeploy affected services after dependency updates.
  • Monitor application latency and CPU anomalies around request parsing.

Validation and detection

  • Search package manifests and lockfiles for es6-crawler-detect versions below 3.1.3.
  • Confirm whether request User-Agent headers are passed into this library.
  • Check runtime dependency trees in deployed artifacts, not only source repositories.
  • Verify updated builds resolve es6-crawler-detect to 3.1.3 or later.
  • Review logs for abnormal CPU or latency tied to header processing.
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

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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CVE-2020-28501 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
Medium
CVSS
5.3 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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
3Source 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
5.3CVSS 3.1MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L3.91.4Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

5.3Medium
CVSS 3.1 vector shape for CVE-2020-28501Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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/aes6-crawler-detectunspecifiedListed
Weakness

CWE details

No CWE listed

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