How severe is CVE-2023-48631?

CVE-2023-48631 has a CVSS score of 5/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2023-48631?

CVE-2023-48631 affects the following packages: @adobe/css-tools (npm). Ecosystems affected: npm.

How do I fix CVE-2023-48631?

Update @adobe/css-tools to 4.3.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-48631 is resolved across your whole dependency graph.

How do I detect CVE-2023-48631 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @adobe/css-tools, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2023-48631 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is CVE-2023-48631 actively exploited in the wild?

No public exploit code has been indexed for CVE-2023-48631 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2023-48631?

CVE-2023-48631 has an EPSS (Exploit Prediction Scoring System) score of 1.1%, placing it in the 65th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2023-48631?

CVE-2023-48631 is classified as Improper Input Validation (CWE-20), CWE-1333 (CWE-1333). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2023-48631 published, and has it been updated?

CVE-2023-48631 was published on November 30, 2023 and was last updated on May 4, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

MEDIUM severity

CVE-2023-48631 — @adobe/css-tools

MEDIUMFix: adobe/css-tools#249

CVE-2023-48631 is a medium-severity (CVSS 5) Improper Input Validation vulnerability in @adobe/css-tools. A fix is available for @adobe/css-tools — see the affected versions and patch details below.

@adobe/css-tools Improper Input Validation and Inefficient Regular Expression Complexity

Published

Nov 30, 2023

Updated

May 4, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.1%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs65th percentile — riskier than 65% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

65other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

@adobe/css-toolsnpm

63.7Mdownloads / week

Description

Impact

@adobe/css-tools version 4.3.1 and earlier are affected by an Improper Input Validation vulnerability that could result in a denial of service while attempting to parse CSS.

Patches

The issue has been resolved in 4.3.2.

Workarounds

None

References

N/A

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`@adobe/css-tools`	all versions	4.3.2`npm install @adobe/css-tools@4.3.2`

Affected Products

1 product · 1 configurations

Application

css-toolsadobe

< 4.3.2

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @adobe/css-tools, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @adobe/css-tools to 4.3.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-48631 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

The Regular Expression Denial of Service (ReDoS) vulnerability in css-tools, triggered by improper input validation when parsing CSS, is considered of moderate severity. While it can lead to a denial of service by causing the application to become unresponsive, the impact is limited to scenarios where an attacker can…

Workaround published by Red Hat

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

Source: Red Hat security advisory for CVE-2023-48631 (CC BY 4.0)

Product	Fixed in	Advisory
Migration Toolkit for Runtimes 1 on RHEL 8	`mtr/mtr-operator-bundle:1.2-23`	RHSA-2024:3919
MTA-6.2-RHEL-9	`mta/mta-windup-addon-rhel9:6.2.3-2`	RHSA-2024:3989
MTA-7.0-RHEL-9	`mta/mta-cli-rhel9:7.0.3-16`	RHSA-2024:3316
RHDH-1.1-RHEL-9	`rhdh/rhdh-hub-rhel9:1.1-97`	RHEA-2024:1366
RHODF-4.15-RHEL-9	`odf4/odf-console-rhel9:v4.15.0-57`	RHSA-2024:1383

Frequently Asked Questions

### Impact @adobe/css-tools version 4.3.1 and earlier are affected by an Improper Input Validation vulnerability that could result in a denial of service while attempting to parse CSS. ### Patches The issue has been resolved in 4.3.2. ### Workarounds None ### References N/A