CVE-2023-39532 [Critical] | Input Validation Bypass in Ses

SES is a JavaScript environment that allows safe execution of arbitrary programs in Compartments. In version 0.18.0 prior to 0.18.7, 0.17.0 prior to 0.17.1, 0.16.0 prior to 0.16.1, 0.15.0 prior to 0.15.24, 0.14.0 prior to 0.14.5, an 0.13.0 prior to 0.13.5, there is a hole in the confinement of guest applications under SES that may manifest as either the ability to exfiltrate information or execute arbitrary code depending on the configuration and implementation of the surrounding host. Guest program running inside a Compartment with as few as no endowments can gain access to the surrounding host’s dynamic import by using dynamic import after the spread operator, like `{...import(arbitraryModuleSpecifier)}`. On the web or in web extensions, a Content-Security-Policy following ordinary best practices likely mitigates both the risk of exfiltration and execution of arbitrary code, at least limiting the modules that the attacker can import to those that are already part of the application. However, without a Content-Security-Policy, dynamic import can be used to issue HTTP requests for either communication through the URL or for the execution of code reachable from that origin. Within an XS worker, an attacker can use the host’s module system to the extent that the host has been configured. This typically only allows access to module code on the host’s file system and is of limited use to an attacker. Within Node.js, the attacker gains access to Node.js’s module system. Importing the powerful builtins is not useful except insofar as there are side-effects and tempered because dynamic import returns a promise. Spreading a promise into an object renders the promises useless. However, Node.js allows importing data URLs, so this is a clear path to arbitrary execution. Versions 0.18.7, 0.17.1, 0.16.1, 0.15.24, 0.14.5, and 0.13.5 contain a patch for this issue. Some workarounds are available. On the web, providing a suitably constrained Content-Security-Policy mitigates most of the threat. With XS, building a binary that lacks the ability to load modules at runtime mitigates the entirety of the threat. That will look like an implementation of `fxFindModule` in a file like `xsPlatform.c` that calls `fxRejectModuleFile`.

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#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-05-03	1.35%	1.80%	+0.44%
2	2026-03-04	0.44%	1.35%	+0.91%
3	2026-03-01	—	0.44%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-05-03

1.35%

1.80%

+0.44%

2026-03-04

0.44%

1.35%

+0.91%

2026-03-01

—

0.44%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
9.8	3.1	CRITICAL	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	3.9	5.9	[email protected]
9.8	3.1	CRITICAL	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	3.9	5.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

9.8

3.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

3.9

5.9

[email protected]

9.8

3.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

3.9

5.9

[email protected]

Affected software / configurations for CVE-2023-39532

Vendor	Product	Version	Raw CPE
agoric	ses	>= 0.13.0, < 0.13.5	cpe:2.3:a:agoric:ses::::::node.js::*
agoric	ses	>= 0.14.0, < 0.14.5	cpe:2.3:a:agoric:ses::::::node.js::*
agoric	ses	>= 0.15.0, < 0.15.24	cpe:2.3:a:agoric:ses::::::node.js::*
agoric	ses	>= 0.18.0, < 0.18.7	cpe:2.3:a:agoric:ses::::::node.js::*
agoric	ses	0.16.0	cpe:2.3:a:agoric:ses:0.16.0:::::node.js::
agoric	ses	0.17.0	cpe:2.3:a:agoric:ses:0.17.0:::::node.js::

References for CVE-2023-39532

URL	Tags
https://github.com/endojs/endo/commit/fc90c6429604dc79ce8e3355e236ccce2bada041	Patch
https://github.com/endojs/endo/security/advisories/GHSA-9c4h-3f7h-322r	Exploit Patch Vendor Advisory

URL

CVE-2023-39532 | SES's dynamic import and spread operator provides possible path to arbitrary exfiltration and execution

Public exploit references (Exploit-DB) for CVE-2023-39532

Exploit prediction scoring system (EPSS) score for CVE-2023-39532

Common vulnerability scoring system (CVSS) metrics for CVE-2023-39532

Weakness enumeration for CVE-2023-39532

GitHub Security Advisory for CVE-2023-39532

Affected software / configurations for CVE-2023-39532

References for CVE-2023-39532