CVE-2026-12866
expr-eval Code Execution via toJSFunction
Description
All versions of the package expr-eval are vulnerable to Code Execution via the toJSFunction() API. An attacker can execute arbitrary JavaScript by supplying crafted expressions that are compiled into native code using new Function(). Because user-controlled expressions are transformed directly into executable JavaScript, attackers can escape the intended expression sandbox and run arbitrary code within the application's context.
INFO
Published Date :
June 23, 2026, 5:17 a.m.
Last Modified :
July 7, 2026, 7:16 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-12866
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | CRITICAL | [email protected] | ||||
| CVSS 4.0 | CRITICAL | [email protected] |
Solution
- Update the expr-eval package to a secure version.
- Avoid compiling untrusted user input directly.
Public PoC/Exploit Available at Github
CVE-2026-12866 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-12866.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-12866 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-12866
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Automated daily security intelligence for blockchain / smart-contract bug bounty hunting.
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-12866 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-12866 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by [email protected]
Jul. 07, 2026
Action Type Old Value New Value Added Reference https://security.snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-17662018 Changed Affected [{'vendor': 'n/a', 'product': 'expr-eval', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '*', 'versionType': 'semver'}]}] [{'vendor': 'n/a', 'product': 'expr-eval', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '*', 'versionType': 'semver'}]}, {'vendor': 'n/a', 'product': 'org.webjars.npm:expr-eval', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '*', 'versionType': 'semver'}]}] -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 23, 2026
Action Type Old Value New Value Added CWE CWE-94 Added Reference https://security.snyk.io/vuln/SNYK-JS-EXPREVAL-15054690 Added SSVC {'id': 'CVE-2026-12866', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'yes'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-06-23T12:06:04.423419Z'} -
New CVE Received by [email protected]
Jun. 23, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'n/a', 'product': 'expr-eval', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '*', 'versionType': 'semver'}]}] Added Description All versions of the package expr-eval are vulnerable to Code Execution via the toJSFunction() API. An attacker can execute arbitrary JavaScript by supplying crafted expressions that are compiled into native code using new Function(). Because user-controlled expressions are transformed directly into executable JavaScript, attackers can escape the intended expression sandbox and run arbitrary code within the application's context. Added CVSS V4.0 AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/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 Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Added CWE CWE-94 Added Reference https://github.com/silentmatt/expr-eval/blob/master/src/expression.js%23L55 Added Reference https://github.com/silentmatt/expr-eval/issues/292 Added Reference https://security.snyk.io/vuln/SNYK-JS-EXPREVAL-15054690