LiveActive security incident?Get immediate response
CVE Record

CVE-2021-23388: Regular Expression Denial of Service (ReDoS)

The package forms before 1.2.1, from 1.3.0 and before 1.3.2 are vulnerable to Regular Expression Denial of Service (ReDoS) via email validation.

MediumCVSS 5.3Not KEV-listedUpdated
Discuss exposureBack to CVEs
Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-23388 is a denial-of-service issue in the npm package forms. Certain versions can spend excessive CPU time when validating crafted email input, potentially slowing or interrupting services that expose affected form validation to users.

Executive priority

Treat as a routine but real availability risk. Prioritize remediation where affected email validation is internet-facing or unauthenticated; lower priority for internal-only or unreachable code paths.

Technical view

The affected forms versions use vulnerable email-validation regular expression behavior that can trigger Regular Expression Denial of Service. The CVSS vector is network-accessible, low complexity, no privileges, no user interaction, unchanged scope, and limited availability impact only.

Likely exposure

Exposure is most likely in Node.js applications using forms before 1.2.1, or 1.3.0 through before 1.3.2, especially on public routes accepting email input.

Exploitation context

The source bundle does not show CISA KEV listing or cited evidence of active exploitation. The risk is service degradation, not data theft or integrity compromise, based on the CVSS impacts provided.

Researcher notes

Evidence supports a ReDoS flaw in email validation with fixed-version boundaries. The bundle does not include CWE mapping, exploit-in-the-wild proof, or detailed operational mitigations beyond upgrading and dependency validation.

Mitigation direction

  • Upgrade forms to a non-affected version, such as 1.2.1 or 1.3.2 or later.
  • Check direct and transitive dependencies for vulnerable forms versions.
  • Review vendor and advisory guidance before relying on compensating controls.
  • Limit exposure of unauthenticated endpoints that invoke affected email validation.

Validation and detection

  • Inspect package manifests and lockfiles for forms versions in affected ranges.
  • Confirm dependency scanning no longer reports CVE-2021-23388.
  • Identify public routes or APIs that validate email through forms.
  • Monitor affected services for unusual CPU spikes or request latency.
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.

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.

cve · low confidence lookup

CVE-2021-23388 mapping review

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

Open ATT&CK lookup
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
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
5.3CVSS 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-2021-23388Attack 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/aformsunspecified, 1.3.0, unspecifiedListed
Weakness

CWE details

No CWE listed

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