Critical severity · published Aug 25, 2026
CVE-2026-55536
Browser Server WebSocket origin validation bypass via unanchored regex (patch bypass of CVE-2026-40289 / GHSA-8x8f-54wf-vv92)
9.1
CVSS
0.5%
EPSS
No
On KEV
Description
PraisonAI is a multi-agent teams system. Prior to praisonai 4.6.58, Browser Server _handle_connection() checks Chrome extension origins with re.match() and the unanchored expression chrome-extension://[a-z0-9]{32}. Extra trailing characters pass before websocket.accept(), allowing start_session commands and unauthorized browser automation. This issue is fixed in version 4.6.58.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 44% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
PR
PraisonAI · MervinPraison
< 4.6.58 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-55536
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-55536
github.com
https://github.com/MervinPraison/PraisonAI/commit/2f9677abb2ea68eab864ee8b6a828fd0141612e1
github.com
https://github.com/MervinPraison/PraisonAI/releases/tag/v4.6.58
github.com
https://github.com/MervinPraison/PraisonAI/security/advisories/GHSA-6g6r-q6gw-w8fg
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