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VulnerabilityPublished

CVE-2026-71555: THM-Health PILOS · Use of Web Link to Untrusted Target with window.opener Access

Affects THM-Health PILOSSource CVE Database V5

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Not known to be exploited · CVSS 4.1 Medium : upgrade to 4.14.1 when convenient.

Data as of 5 Nov 2026, 00:01 UTC

CVSS 3.1 base score
4.1Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 21% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 4.14.1
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 6 Aug 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.

What to do

Upgrade PILOS and thm-health/PILOS to 4.14.1.

Affected software

ProductAffectedFixed in
THM-HealthPILOSAffected
  • >=2.1.0 <4.14.1
Fixed in
  • 4.14.1
GitHubthm-health/PILOSpkg:github/thm-health/PILOSOther threatsAffected
  • <4.14.1 >=2.1.0
Fixed in
  • 4.14.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade PILOS to version 4.14.1 or later, where the Cross-Origin-Opener-Policy header is properly set to prevent window.opener access from untrusted targets. Patch status is not explicitly confirmed but fixed in 4.14.1 per the description.

Description

PILOS, a frontend for BigBlueButton, versions from 2.1.0 up to but not including 4.14.1, does not set the Cross-Origin-Opener-Policy header. This allows pages opened with target="_blank" to retain a window.opener reference, enabling reverse tabnabbing attacks where a malicious page can manipulate the original PILOS tab. The issue is fixed in version 4.14.1.

References

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