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01 Record

CVE-2026-12866

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

CriticalPUBLISHEDCNA: snyk
CNA base score9.2 CVSS v4.0CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
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02 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

03 Exploitation and scoring

Exploitation
Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.
SSVC decision
  • ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
  • AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
  • Technical ImpacttotalSuccessful exploitation gives total control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
0.86% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 58.3% of scored records. A rank, not a probability.
NVD base score
9.2 (CVSS v4.0), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:4.0/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
NVD analysis status
Deferred. NVD last modified this record on 2026-07-07.
Red Hat severity
Low. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2026-06-23 05:00Z4 MO AGO
Last updated
2026-08-14 15:25Z2 MO AGO
Reserved
2026-06-22
Assigning CNA
snyk
Record state
PUBLISHED
Severity
Critical (CVSS 9.2)
CNA CVSS vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Weaknesses
  • CWE-94Improper Control of Generation of Code ('Code Injection')Base
Data version
5.2
Document digest
a1220016250cee39b898018a4aef527dc7126c8939b611985335c8dbf18eaca7

05 Affected products

VendorProductVersionsPlatforms
n/aexpr-eval0 to < *—
n/aorg.webjars.npm:expr-eval0 to < *—

06 References