vulnerability / NVI-00013885 / Revision 2
PraisonAI has a Browser Server WebSocket origin validation bypass via unanchored regex (patch bypass of CVE-2026-40289 / GHSA-8x8f-54wf-vv92)
GitHub lists this reviewed advisory for PraisonAI. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
9.1 critical
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
0.521%
FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.44274. Missing scores are unknown.
As of · FIRST EPSS
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
PraisonAI
source listed< 4.6.58
### Summary `praisonai/browser/server.py` validates incoming WebSocket connections using a Chrome extension Origin check. The regex `chrome-extension://[a-z0-9]{32}` is applied with `re.match()`, which **only anchors at the start of the string, not the end**. Any Origin header with more than 32 alphanumeric characters after `chrome-extension://` — including non-alphanumeric trailing characters — passes the check. This is a **patch bypass** of GHSA-8x8f-54wf-vv92. That advisory triggered the addition of origin validation; this finding shows the validation is bypassable by any WebSocket client that forges an Origin header. After bypassing, the attacker can send `start_session` commands that are executed by any Chrome extension currently connected to the server — causing the extension to perform arbitrary browser automation including cookie theft and screenshot capture. ### Details **Vulnerable code — `browser/server.py` line 186:** ```python elif parsed_origin.scheme == "chrome-extension" and \ re.match(r"chrome-extension://[a-z0-9]{32}", origin): is_allowed = True ``` `re.match()` returns a match object if the pattern matches at the **beginning** of the string; traili
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. FIRST EPSS
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-6g6r-q6gw-w8fg ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
- CVE-2026-55536 ↗
FIRST EPSS · official catalog
Observed . FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 2 ·
Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.