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

Exp

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.

Published: 2021-04-12 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-23368 is rated High Exploit Risk (69.4/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 3.51%). 2 public exploit reference(s) are indexed (Exploit-DB). EPSS rose +2.50% over the last day, indicating growing attacker interest. Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2021-23368

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-23368

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 1.01% 3.51% +2.50%
2 2026-06-03 0.26% 1.01% +0.75%
3 2026-06-02 — 0.26% —

Full EPSS history (21 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-23368

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 1.4 [email protected]
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 1.4 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2021-23368

GitHub Security Advisory for CVE-2021-23368

GHSA-hwj9-h5mp-3pm3 · Severity: medium · Ecosystem: npm — Regular Expression Denial of Service in postcss

OS Trackers for CVE-2021-23368

vendor priority summary link
debian not yet assigned CVE-2021-23368 not yet assigned priority: Debian including 1 source packages (node-postcss), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-23368
redhat medium — https://access.redhat.com/security/cve/CVE-2021-23368
ubuntu medium CVE-2021-23368 medium priority: Ubuntu including 1 source packages (node-postcss), 16 status rows across 16 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 7, ignored 4, DNE 3, needed 1, released 1. https://ubuntu.com/security/CVE-2021-23368

Affected software / configurations for CVE-2021-23368

Vendor Product Version Raw CPE
postcss postcss >= 7.0.0, < 7.0.36 cpe:2.3:a:postcss:postcss:*:*:*:*:*:node.js:*:*
postcss postcss >= 8.0.0, < 8.2.10 cpe:2.3:a:postcss:postcss:*:*:*:*:*:node.js:*:*

References for CVE-2021-23368

URL Tags
https://github.com/postcss/postcss/commit/8682b1e4e328432ba692bed52326e84439cec9e4 Patch Third Party Advisory
https://github.com/postcss/postcss/commit/b6f3e4d5a8d7504d553267f80384373af3a3dec5 Patch Third Party Advisory
https://lists.apache.org/thread.html/r00158f5d770d75d0655c5eef1bdbc6150531606c8f8bcb778f0627be%40%3Cdev.myfaces.apache.org%3E
https://lists.apache.org/thread.html/r16e295b4f02d81b79981237d602cb0b9e59709bafaa73ac98be7cef1%40%3Cdev.myfaces.apache.org%3E
https://lists.apache.org/thread.html/r49afb49b38748897211b1f89c3a64dc27f9049474322b05715695aab%40%3Cdev.myfaces.apache.org%3E
https://lists.apache.org/thread.html/r5acd89f3827ad9a9cad6d24ed93e377f7114867cd98cfba616c6e013%40%3Ccommits.myfaces.apache.org%3E
https://lists.apache.org/thread.html/r8def971a66cf3e375178fbee752e1b04a812a047cc478ad292007e33%40%3Cdev.myfaces.apache.org%3E
https://lists.apache.org/thread.html/rad5af2044afb51668b1008b389ac815a28ecea9eb75ae2cab5a00ebb%40%3Ccommits.myfaces.apache.org%3E
https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-1244795 Exploit Patch Third Party Advisory
https://snyk.io/vuln/SNYK-JS-POSTCSS-1090595 Exploit Patch Third Party Advisory
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