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CVE Record

CVE-2021-23382: Regular Expression Denial of Service (ReDoS)

The package postcss before 8.2.13 are vulnerable to Regular Expression Denial of Service (ReDoS) via getAnnotationURL() and loadAnnotation() in lib/previous-map.js. The vulnerable regexes are caused mainly by the sub-pattern \/\*\s* sourceMappingURL=(.*).

MediumCVSS 5.3Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-23382 is a denial-of-service issue in PostCSS before 8.2.13. A specially crafted source map annotation can make vulnerable regular expressions consume excessive CPU. The documented impact is availability only, not data theft or code execution.

Executive priority

Treat as a routine but necessary dependency update. Prioritize internet-facing or multi-tenant systems that process customer-supplied CSS, because the business impact is service availability degradation rather than compromise.

Technical view

The issue is a ReDoS in getAnnotationURL() and loadAnnotation() in lib/previous-map.js, tied to regex handling of sourceMappingURL annotations. CVSS 3.1 is 5.3 with network attack vector, no privileges or user interaction, and low availability impact.

Likely exposure

Exposure is most likely in applications, build pipelines, or services using PostCSS before 8.2.13, especially where CSS or source map comments may be supplied by untrusted users or external content.

Exploitation context

The source bundle does not show CISA KEV listing or active exploitation evidence. The plausible risk is service slowdown or interruption when vulnerable PostCSS parsing handles attacker-controlled input.

Researcher notes

Evidence identifies vulnerable regex handling in previous-map.js and an upstream fixing commit. The bundle does not provide exploitation reports, detailed affected version ranges beyond before 8.2.13, or product impact outside PostCSS-related packages.

Mitigation direction

  • Upgrade PostCSS to 8.2.13 or later.
  • Update transitive dependencies that bundle vulnerable PostCSS versions.
  • Check Snyk and upstream PostCSS guidance for package-specific remediation.
  • Reduce or isolate processing of untrusted CSS where immediate upgrade is delayed.
  • Use dependency pinning or overrides to prevent vulnerable versions returning.

Validation and detection

  • Inventory package lockfiles, SBOMs, and dependency trees for PostCSS versions.
  • Confirm no runtime or build path uses PostCSS before 8.2.13.
  • Review whether user-supplied CSS or source maps reach PostCSS parsing.
  • Run dependency scanning after upgrades to confirm the finding is closed.
  • For WebJars usage, verify org.webjars.npm packaging is not vulnerable.
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

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CVE-2021-23382 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
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-2021-23382Attack 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/apostcssunspecifiedListed
Weakness

CWE details

No CWE listed

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