CVE-2021-33587: The css-what package 4.0.0 through 5.0.0 for Node.js does not ensure that attribute parsing has Linear Time Co

Q: How do I fix CVE-2021-33587?

css-what: downgrade or apply the listed mitigation; e-series performance analyzer: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2021-33587 being exploited?

CVE-2021-33587 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-33587 affect?

CVE-2021-33587 affects css-what, e-series performance analyzer. Severity is high (CVSS 7.5). The css-what package 4.0.0 through 5.0.0 for Node.js does not ensure that attribute parsing has Linear Time Complexity relative to the size of the input.

Q: How urgent is CVE-2021-33587?

Priority 52/100. High severity; Remotely exploitable, no login, no user action

This month

HIGH 7.5REMOTEDOWNGRADEMITIGATE

CVE-2021-33587 is a high-severity flaw (CVSS 7.5) affecting css-what, e-series performance analyzer. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The css-what package 4.0.0 through 5.0.0 for Node.js does not ensure that attribute parsing has Linear Time Complexity relative to the size of the input.

Why this priority

High severity
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.0% (top 19%)
CISA exploited list	No
Published	2021-05-28
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: css-what project · netapp

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-05-28 20:15 UTCPublished CVE record published
2026-06-17 03:54 UTCUpdated Record last modified

css-what project css-what DOWNGRADE

Affected: 4.0.0 · 5.0.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.0.0

1. Check installed version

npm ls css-what

2. No fixed release: DOWNGRADE to a release before 4.0.0

npm view css-what versions npm install css-what@"<4.0.0"

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

netapp e-series performance analyzer MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy e-series-performance-analyzer || rpm -q e-series-performance-analyzer || e-series-performance-analyzer --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-33587?

css-what: downgrade or apply the listed mitigation; e-series performance analyzer: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-33587 being exploited?

CVE-2021-33587 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-33587 affect?

CVE-2021-33587 affects css-what, e-series performance analyzer. Severity is high (CVSS 7.5). The css-what package 4.0.0 through 5.0.0 for Node.js does not ensure that attribute parsing has Linear Time Complexity relative to the size of the input.

How urgent is CVE-2021-33587?

Priority 52/100. High severity; Remotely exploitable, no login, no user action

Software pages

Node.js vulnerabilities

Related CVEs

CVE-2022-21222 MEDIUM 5.3 UPGRADE The package css-what before 2.1.3 are vulnerable to Regular Expression Denial of Service (ReDoS) due to the us

References

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