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Fencer Vulns
critical 10.0

CVE-2026-93606 json

vm2 before 3.12.1 Sandbox Escape via Promise Symbol.species

published 2026-09-18 52 d ago modified 2026-09-18 51 d ago also EUVD-2026-82901

cvss
10.0
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.7%
EPSS 0.7% chance of exploitation in 30 days, percentile 53%
public exploits
0
none known

Summary

vm2 (npm) versions 3.12.0 and earlier contain a sandbox escape in `VM` and `NodeVM`. When an embedder exposes a host API that returns a host-realm Promise, the bridge's rejection sanitizer (hostPromiseSanitizeReject / makeSanitizedPromiseCallback / normalizeHostPromiseCallbacks in lib/bridge.js) only wraps `then`/`catch` rejection slots that hold a function, and the sandbox-side `Symbol.species`/`.then` neutralization is installed only on the sandbox intrinsic `Promise.prototype`, so it never applies to a host Promise. Code running inside the sandbox can overwrite `p.constructor[Symbol.species]` on the host Promise and then call `p.then()` with no `onRejected` handler; V8 substitutes its internal Thrower, which re-throws the raw host rejection value into a resolve/reject closure captured by the attacker. This delivers an unsanitized, fully functional bridge proxy of the host object to sandboxed code, bypassing handleException and hostPromiseSanitizeReject. If the rejection value is host-pivotable (for example a host `process` object), this results in arbitrary code execution on the host. Fixed in 3.12.1.

Patch / fix

  • patriksimek vm2 3.12.1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-93606 updated cvss 9.8

vm2: vm2 before 3.12.1 Sandbox Escape via Promise Symbol.species

  • Red Hat Ansible Automation Platform 2.1 ansible-automation-platform/automation-portal 1791295379
    fixed: vendor fix “Until the fix is applied, do not expose host functions that return host-realm Promise objects to VM/NodeVM. Return only serialized primitives, or keep host work fully outside the sandbox.” RHSA-2026:80603
  • Red Hat Ansible Automation Platform 2.2 ansible-automation-platform/automation-portal 1791293780, ansible-automation-platform/bootc-automation-portal-rhel9 1791865660
    fixed: vendor fix “Until the fix is applied, do not expose host functions that return host-realm Promise objects to VM/NodeVM. Return only serialized primitives, or keep host work fully outside the sandbox.” RHSA-2026:80644
  • Red Hat Developer Hub 1.9 rhdh/rhdh-hub-rhel9 1793117813
    fixed: vendor fix “Until the fix is applied, do not expose host functions that return host-realm Promise objects to VM/NodeVM. Return only serialized primitives, or keep host work fully outside the sandbox.” RHSA-2026:91651
  • Red Hat Developer Hub 1.10 rhdh/rhdh-hub-rhel9 1791311495, rhdh/red-hat-developer-hub-backstage-plugin-lightspeed-backend 1791242697, rhdh/red-hat-developer-hub-backstage-plugin-orchestrator-backend 1791251282
    fixed: vendor fix “Until the fix is applied, do not expose host functions that return host-realm Promise objects to VM/NodeVM. Return only serialized primitives, or keep host work fully outside the sandbox.” RHSA-2026:76788
  • Red Hat Developer Hub 1.9 rhdh/rhdh-rhel9-operator 1793117972, rhdh/rhdh-operator-bundle 1793126835 Red Hat Developer Hub 1.10 rhdh/rhdh-rhel9-operator 1791219676, rhdh/rhdh-operator-bundle 1791315788, rhdh/rhdh-must-gather-rhel9 1788278523, rhdh/rhdh-rag-content-rhel9 1791168570, rhdh/red-hat-developer-hub-backstage-plugin-lightspeed 1791242743, rhdh/red-hat-developer-hub-backstage-plugin-orchestrator 1791250003, +3 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
total
Assessed
51 d ago

Exploit prediction

0.71% chance of exploitation in the next 30 days, higher than 53% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/patriksimek/vm2/security/advisories/GHSA-6454-5x88-m6jw referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 10.0 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
CNA 3.1 10.0 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
CNA 4.0 10.0 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/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

Affected products

  • patriksimek vm2

Classification

Weakness
  • CWE-693 Protection Mechanism Failure

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.