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CVE Record

CVE-2021-23368: Regular Expression Denial of Service (ReDoS)

The package postcss from 7.0.0 and before 8.2.10 are vulnerable to Regular Expression Denial of Service (ReDoS) during source map parsing.

MediumCVSS 5.3Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-23368 is a denial-of-service issue in PostCSS source map parsing. A maliciously crafted source map can make vulnerable versions spend excessive CPU on regular expression processing. The impact is availability, not data theft or code execution, based on the provided sources.

Executive priority

Treat as a routine but real availability risk. Prioritize remediation in internet-facing build services, SaaS pipelines, and systems processing customer-supplied assets; otherwise handle through standard dependency update cycles.

Technical view

PostCSS versions from 7.0.0 before 8.2.10 are vulnerable to Regular Expression Denial of Service during source map parsing. CVSS 3.1 is 5.3 with network attack vector, low complexity, no privileges, no user interaction, and low availability impact.

Likely exposure

Exposure is most likely in build systems, developer tooling, CI, or services that run vulnerable PostCSS versions and parse source maps from untrusted or externally influenced inputs.

Exploitation context

The bundle does not show active exploitation and marks KEV as false. Exploitation depends on causing vulnerable PostCSS source map parsing to process crafted input; the cited sources do not provide evidence of widespread real-world abuse.

Researcher notes

The key condition is source map parsing in vulnerable PostCSS versions. Public references identify the vulnerable range and remediation commits, but the supplied bundle lacks detailed affected call paths, exploit telemetry, or product-specific impact beyond PostCSS and referenced downstream dependency updates.

Mitigation direction

  • Upgrade PostCSS to version 8.2.10 or later.
  • Update transitive dependencies that pin vulnerable PostCSS versions.
  • Check Java/WebJars packaging if using npm PostCSS through WebJars.
  • Reduce acceptance of untrusted source maps where operationally possible.
  • Follow vendor and package-manager guidance for dependency remediation.

Validation and detection

  • Inventory direct and transitive PostCSS versions in application and build dependencies.
  • Confirm no dependency resolves to PostCSS >=7.0.0 and <8.2.10.
  • Review CI and build pipelines that process externally supplied source maps.
  • Check dependency update PRs for PostCSS remediation coverage.
  • Monitor package advisories for any changed fixed-version guidance.
Prepared
Confidence
high
Sources
7

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-2021-23368 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
11Source 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-2021-23368Attack 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/apostcss7.0.0, 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.