CVE-2026-12209Public exploitNetwork attack vector

Remote code execution via prototype-chain filter lookup

Published Jun 15, 2026 · Updated Jun 15, 2026

Code injection in RubyLouvre Avalon 2.2.10 and earlier allows remote attackers to execute JavaScript through untrusted templates. The Template Filter Handler stores filters in a plain object and resolves names without an own-property check, so constructor traverses the prototype chain and reaches new Function compilation. Remote code execution requires a consuming application to let attackers control template content; ordinary static templates do not expose the demonstrated path.

CVSS severityUnavailable
Unscored
EPSS probability0.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Code injection in RubyLouvre Avalon 2.2.10 and earlier allows remote attackers to execute JavaScript through untrusted templates. The Template Filter Handler stores filters in a plain object and resolves names without an own-property check, so constructor traverses the prototype chain and reaches new Function compilation. Remote code execution requires a consuming application to let attackers control template content; ordinary static templates do not expose the demonstrated path.

The record

CVE
CVE-2026-12209
Published
Jun 15, 2026
Updated
Jun 15, 2026
Vendor
RubyLouvre
Product
Avalon
Classifications
CWE-1321, CWE-94, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 15, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=2.2.0
  2. Affected versionversion=2.2.1
  3. Affected versionversion=2.2.10
  4. Affected versionversion=2.2.2
  5. Affected versionversion=2.2.3
  6. Affected versionversion=2.2.4
  7. Affected versionversion=2.2.5
  8. Affected versionversion=2.2.6
  9. Affected versionversion=2.2.7
  10. Affected versionversion=2.2.8
  11. Affected versionversion=2.2.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

RubyLouvre · Avalonversion=2.2.0; version=2.2.1; version=2.2.10; version=2.2.2; version=2.2.3; version=2.2.4; version=2.2.5; version=2.2.6; version=2.2.7; version=2.2.8; version=2.2.9

Published CVSS scores

5.3VulDB CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:X/RC:R
6.9VulDB CNACVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P
5.0VulDB CNAAV:N/AC:L/Au:N/C:N/I:P/A:N/E:POC/RL:ND/RC:UR
5.3VulDB CNACVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:X/RC:R

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-1321Improperly Controlled Modification of Object Prototype Attributes
CWE-94Improper Control of Generation of Code ('Code Injection')
T1059.007Command and Scripting Interpreter: JavaScript

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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