CVE-2026-55536 — Browser Server WebSocket origin validation bypass via unanchored regex (patch bypass of CVE-2026-40289 / GHSA-8x8f-54wf-vv92)

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.

Published Aug 25, 2026Updated Aug 25, 2026Sources: cvelistV5, GitHub_M

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.

Exploitation

Unreported

no source claims exploitation

EPSS

chance of exploitation in 30 days

Affects

mervinpraison

praisonai

CVSS base

9.1

CRITICAL

Affected scope

The catalog records vendors and products as separate lists, not pairs, so which product belongs to which vendor is not something this page can say.

Vendors (1)

mervinpraison

Products (1)

praisonai

Every base score collected

Sources score independently and disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Source
9.1	CVSS 3.1	CRITICAL	—	—	cvelistV5

Weakness & attack patterns

CWE-284
CWE-625

Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.

T1027.009Obfuscated Files or Information: Embedded Payloads
T1546.004Event Triggered Execution: .bash_profile and .bashrc
T1546.016Event Triggered Execution: Installer Packages

Detection

Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.

Search application, proxy, and WAF logs for requests touching //[a-z0-9].

References

3 on the record

github.com/MervinPraison/PraisonAI/security/advisories/GHSA-6g6r-q6gw-w8fg
x_refsource_CONFIRM
github.com/MervinPraison/PraisonAI/commit/2f9677abb2ea68eab864ee8b6a828fd0141612e1
x_refsource_MISC
github.com/MervinPraison/PraisonAI/releases/tag/v4.6.58
x_refsource_MISC

Elsewhere on this site

mervinpraisonevery CVE for this vendor
CWE-284other pages naming this weakness

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.