CVE-2021-23354Public exploitNetwork attack vector

Service interruption via cubic regex backtracking

Published Mar 12, 2021 · Updated Sep 17, 2024

Regular expression denial of service in Adaltas printf before 0.6.1 allows remote attackers to interrupt service via a crafted format string. Formatter.prototype._re applies a nested repetition to invalid format text, causing cubic worst-case backtracking in lib/printf.js. Exploitation requires a consuming application to pass an attacker-controlled format string, resulting in excessive CPU use and processing delays.

CVSS severity7.5
High
EPSS probability2.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Regular expression denial of service in Adaltas printf before 0.6.1 allows remote attackers to interrupt service via a crafted format string. Formatter.prototype._re applies a nested repetition to invalid format text, causing cubic worst-case backtracking in lib/printf.js. Exploitation requires a consuming application to pass an attacker-controlled format string, resulting in excessive CPU use and processing delays.

The record

CVE
CVE-2021-23354
Published
Mar 12, 2021
Updated
Sep 17, 2024
Vendor
Adaltas
Product
printf
Classifications
CWE-1333, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 12, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <0.6.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Adaltas · printfversion=unspecified <0.6.1

Published CVSS scores

5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
5.3SnykCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-1333Inefficient Regular Expression Complexity
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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