CVE-2020-26303Public exploitNetwork attack vector

Service interruption via rstart exponential backtracking

Published Oct 26, 2024 · Updated Oct 28, 2024

Regular expression denial of service in Nicolás Bevacqua's insane 2.6.2 and earlier allows attackers to hang sanitization via crafted HTML. The rstart expression processes attacker-controlled attribute text with ambiguous overlapping matches, causing exponential backtracking during parsing. Any application that passes untrusted HTML to the sanitizer can have its calling process consume CPU indefinitely, interrupting service without data exposure or modification.

CVSS severity8.7
High
EPSS probability0.54%
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 Nicolás Bevacqua's insane 2.6.2 and earlier allows attackers to hang sanitization via crafted HTML. The rstart expression processes attacker-controlled attribute text with ambiguous overlapping matches, causing exponential backtracking during parsing. Any application that passes untrusted HTML to the sanitizer can have its calling process consume CPU indefinitely, interrupting service without data exposure or modification.

The record

CVE
CVE-2020-26303
Published
Oct 26, 2024
Updated
Oct 28, 2024
Vendor
Nicolás Bevacqua
Product
insane
Classifications
CWE-1333, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 26, 2024CVE publishedPublication date reported by the CVE source.
  2. Oct 28, 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=0 <=2.6.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Nicolás Bevacqua · insaneversion=0 <=2.6.2

Published CVSS scores

8.7GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Green
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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
T1499.004Application 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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