CVE-2026-73646Network attack vectorHinoki check available

Arbitrary .map disclosure via sourceMappingURL traversal

Published Aug 17, 2026 · Updated Aug 17, 2026

Path traversal in PostCSS before 8.5.18 allows remote attackers to read arbitrary .map file contents via crafted CSS comments. In lib/previous-map.js, loadMap() resolves the untrusted sourceMappingURL annotation against dirname(opts.from), and loadFile() reads the resulting path after only a .map suffix check, so ../ segments can escape the intended directory. Exposure requires an application to process untrusted CSS without map: false; when the reached source map contains sourcesContent, PostCSS copies that data into result.map for disclosure.

CVSS severity7.5
High
EPSS probability0.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Path traversal in PostCSS before 8.5.18 allows remote attackers to read arbitrary .map file contents via crafted CSS comments. In lib/previous-map.js, loadMap() resolves the untrusted sourceMappingURL annotation against dirname(opts.from), and loadFile() reads the resulting path after only a .map suffix check, so ../ segments can escape the intended directory. Exposure requires an application to process untrusted CSS without map: false; when the reached source map contains sourcesContent, PostCSS copies that data into result.map for disclosure.

The record

CVE
CVE-2026-73646
Published
Aug 17, 2026
Updated
Aug 17, 2026
Vendor
PostCSS
Product
PostCSS
Classifications
CWE-22, T1005
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 17, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 8.5.18

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

PostCSS · PostCSSversion=< 8.5.18

Published CVSS scores

7.5GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
T1005Data from Local System

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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