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Fencer Vulns
low 3.1

CVE-2026-4958 json

OpenBMB XAgent WebSocket Endpoint replayer.py ReplayServer.send_data authorization

published 2026-03-27 7 mo ago modified 2026-10-26 13 d ago also EUVD-2026-16690

cvss
3.1
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 34%
public exploits
0
none known

Summary

A vulnerability has been found in OpenBMB XAgent 1.0.0. This affects the function ReplayServer.on_connect/ReplayServer.send_data of the file XAgentServer/application/websockets/replayer.py of the component WebSocket Endpoint. Such manipulation of the argument interaction_id leads to authorization bypass. The attack may be launched remotely. Attacks of this nature are highly complex. The exploitability is reported as difficult. The exploit has been disclosed to the public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

CISA SSVC

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

Exploit prediction

0.40% chance of exploitation in the next 30 days, higher than 34% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • gist.github.com https://gist.github.com/YLChen-007/dc46c2a710ecb9e855695f32da8bcab5 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 2.3 CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P
CNA 3.1 3.1 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N/E:P/RL:X/RC:R
CNA 3.0 3.1 CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N/E:P/RL:X/RC:R
CNA 2.0 2.1 AV:N/AC:H/Au:S/C:P/I:N/A:N/E:POC/RL:ND/RC:UR
CNA 4.0 1.3 CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/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 3.1 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
CNA 2.0 2.1 AV:N/AC:H/Au:S/C:P/I:N/A:N

Affected products

  • OpenBMB XAgent

Classification

Weakness
  • CWE-639 Authorization Bypass Through User-Controlled Key
  • CWE-285 Improper Authorization

References

Sources

Fencer Vulns 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.