CVE-2020-26311Public exploitNetwork attack vector

Service interruption via exponential HbbTV regex backtracking

Published Oct 26, 2024 · Updated Oct 28, 2024

Regular expression denial of service in 3rd-Eden useragent 2.3.0 and earlier allows remote attackers to interrupt services via crafted user-agent strings. The HbbTV device parser applies a pattern with overlapping repeated groups to attacker-controlled input, causing exponential backtracking as repeated SW-Version tokens fail to complete the match. Applications become reachable when they pass network-supplied User-Agent values to the parser, and the resulting CPU exhaustion can make the hosting Node.js process unresponsive.

CVSS severity8.7
High
EPSS probability0.52%
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 3rd-Eden useragent 2.3.0 and earlier allows remote attackers to interrupt services via crafted user-agent strings. The HbbTV device parser applies a pattern with overlapping repeated groups to attacker-controlled input, causing exponential backtracking as repeated SW-Version tokens fail to complete the match. Applications become reachable when they pass network-supplied User-Agent values to the parser, and the resulting CPU exhaustion can make the hosting Node.js process unresponsive.

The record

CVE
CVE-2020-26311
Published
Oct 26, 2024
Updated
Oct 28, 2024
Vendor
3rd-Eden
Product
useragent
Classifications
CWE-1333, T1499
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. Affected versionversion=0 <*

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

3rd-Eden · useragentversion=0; version=0 <*

Published CVSS scores

8.7GitHub CNACVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/U:Green
6.6GitHub Advisory DatabaseCVSS: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:U/U:Green

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
T1499Endpoint Denial of Service

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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