Sandbox escape for instances that have enabled transformation functions in matrix-hookshot

published 2023-09-27 3 y ago modified 2026-06-17 4 mo ago also EUVD-2023-48045

cvss: 5.6; 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 24%
public exploits: 0; none known

matrix-hookshot is a Matrix bot for connecting to external services like GitHub, GitLab, JIRA, and more. Instances that have enabled transformation functions (those that have `generic.allowJsTransformationFunctions` in their config), may be vulnerable to an attack where it is possible to break out of the `vm2` sandbox and as a result Hookshot will be vulnerable to this. This problem is only likely to affect users who have allowed untrusted users to apply their own transformation functions. If you have only enabled a limited set of trusted users, this threat is reduced (though not eliminated). Version 4.5.0 and above of hookshot include a new sandbox library which should better protect users. Users are advised to upgrade. Users unable to upgrade should disable `generic.allowJsTransformationFunctions` in the config.

Patch / fix

fixed in 1 links 1

matrix hookshot 4.5.0

github.com/matrix-org/matrix-hookshot@dc126af commit

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 2 y ago (2024-09-20)

Exploit prediction

0.32% chance of exploitation in the next 30 days, higher than 24% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	5.6	CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:L
NVD	3.1	9.0	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

Affected products

matrix-org matrix-hookshot

Classification

Weakness

CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component

References

Sources

CVE List CVE-2023-43656
NVD CVE-2023-43656

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.

Summary