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Fencer Intel
medium 5.5

CVE-2026-81835 json

RooCodeInc Roo-Code MCP Integration Trust Model malicious_mcp_server.py fetch_instructions code injection

published 2mo ago modified 2mo ago also EUVD-2026-67313

cvss
5.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 22%
public exploits
0
none known

Summary

A security vulnerability has been detected in RooCodeInc Roo-Code up to 3.51.1. This affects the function fetch_instructions of the file malicious_mcp_server.py of the component MCP Integration Trust Model. The manipulation leads to code injection. The attack is possible to be carried out remotely. The exploit has been disclosed publicly and may be used. Multiple isses were reported to the vendor beforehand. They explain, that "they all apply to Roo Code, a project we no longer support - the repository was archived a while ago, and we don't encourage anyone to use it." This vulnerability only affects products that are no longer supported by the maintainer.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
2mo ago

Exploit prediction

0.30% chance of exploitation in the next 30 days, higher than 22% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • gist.github.com https://gist.github.com/tchen200311/05b5960272c290b7843d6bbdbfe9f7c1 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 5.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
CNA 3.1 5.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:L/E:P/RL:X/RC:R
CNA 3.0 5.5 CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:L/E:P/RL:X/RC:R
CNA 2.0 6.5 AV:N/AC:L/Au:S/C:P/I:P/A:P/E:POC/RL:ND/RC:UR
CNA 4.0 2.0 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:L/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 5.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:L
CNA 2.0 6.5 AV:N/AC:L/Au:S/C:P/I:P/A:P

Affected products

  • RooCodeInc Roo-Code

Classification

Weakness
  • CWE-94 Improper Control of Generation of Code
  • CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component

References

Sources

Fencer Intel 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.