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Fencer Intel
medium 5.4

CVE-2026-19986 json

Adblock for Youtube Extension Event Listener contentscript.js updateDynamicRules improper authorization

published 2mo ago modified 2mo ago also EUVD-2026-60048

cvss
5.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 36%
public exploits
0
none known

Summary

A weakness has been identified in Adblock for Youtube Extension up to 7.2.1 on Chrome. The impacted element is the function updateDynamicRules of the file contentscript.js of the component Event Listener. This manipulation of the argument yt-anti-adblock-detected causes improper authorization. It is possible to initiate the attack remotely. The exploit has been made available to the public and could be used for attacks. The vendor was contacted early about this disclosure but did not respond in any way.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
2mo ago

Exploit prediction

0.42% chance of exploitation in the next 30 days, higher than 36% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • vuldb.com https://vuldb.com/submit/873935 referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/xryj920/chrome_extensions/blob/main/AdBlock%20Ltd.%20Adblock%20for%20Youtube%207.2.1%20allows%20persistent%20disabling%20of%20ad%20blocking%20through%20an%20unauthenticated%20DOM%20event referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 5.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
CNA 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L/E:P/RL:X/RC:R
CNA 3.0 5.4 CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L/E:P/RL:X/RC:R
CNA 2.0 6.4 AV:N/AC:L/Au:N/C:N/I:P/A:P/E:POC/RL:ND/RC:UR
CNA 4.0 2.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/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:X
CNA 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L
CNA 2.0 6.4 AV:N/AC:L/Au:N/C:N/I:P/A:P

Affected products

  • n/a Adblock for Youtube Extension

Classification

Weakness
  • CWE-285 Improper Authorization
  • CWE-266 Incorrect Privilege Assignment

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.