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Fencer Intel
medium 5.3

CVE-2021-23354 json

Regular Expression Denial of Service (ReDoS)

published 5y ago modified 4mo ago also GHSA-xfhp-gmh8-r8v2 , EUVD-2021-0725

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.2%
EPSS 2.2% chance of exploitation in 30 days, percentile 82%
public exploits
0
none known

Summary

The package printf before 0.6.1 are vulnerable to Regular Expression Denial of Service (ReDoS) via the regex string /\%(?:\(([\w_.]+)\)|([1-9]\d*)\$)?([0 +\-\]*)(\*|\d+)?(\.)?(\*|\d+)?[hlL]?([\%bscdeEfFgGioOuxX])/g in lib/printf.js. The vulnerable regular expression has cubic worst-case time complexity.

Patch / fix

  • npm printf 0.6.1
  • n/a printf 0.6.1

Is CVE-2021-23354 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Exploit prediction

2.18% chance of exploitation in the next 30 days, higher than 82% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/adaltas/node-printf/issues/31 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
npm printf
<0.6.1
0.6.1

Affected products

  • n/a printf

Classification

Weakness
  • CWE-1333 Inefficient Regular Expression Complexity
  • CWE-400 Uncontrolled Resource Consumption

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.