Security Digest · Vulnerability record
CVE-2026-77414: JSONata vulnerable to Arbitrary Code Execution via crafted JSONata expressions
JSONata is a JSON query and transformation language.
CVSS 9.3 Critical EPSS 0.6% · p46
Should you act?
Critical and remotely reachable
No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.6%, percentile 46: FIRST’s model estimates a 0.6% chance of exploitation activity in the next 30 days, higher than 46% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes
jsonata(npm) >= 2.0.0, < 2.2.1, fixed in 2.2.1;jsonata(npm) < 1.8.8, fixed in 1.8.8. Check your lockfile, including transitive dependencies.
What it is
JSONata is a JSON query and transformation language. Prior to 1.8.8 and 2.2.1, the src/jsonata.js environment.lookup function used a bypassable hasOwnProperty check. Crafted expressions could use $hasOwnProperty, $spread, $string, prototype access, and $constructor to reach the object prototype and invoke process.getBuiltinModule with childprocess, executing arbitrary code with the privileges of the host process. This issue is fixed in versions 1.8.8 and 2.2.1.
From the GitHub advisory
Before JSONata 2.2.1 and 1.8.8 it was possible to execute arbitrary code with crafted expressions, due to a bypassable hasOwnProperty check in environment.lookup https://github.com/jsonata-js/jsonata/blob/8ee4476f8a228bfc7a62979ae0a9c13a4043cd03/src/jsonata.js#L1863-L1871
This was fixed in https://github.com/jsonata-js/jsonata/pull/799 (https://github.com/jsonata-js/jsonata/pull/799/files#diff-de23c1b6e199d0e59406a284aae5fa7be63fcbbff706829913dba73dcdeb061cL1865-R1865) which is included in the 2.2.1 release, and then back-ported to the 1.8.8 release.
PoC
Weakness type: CWE-94.
Product: jsonata (npm) · Assigned by: GitHub_M · Published: 2026-08-21
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| npm | jsonata | >= 2.0.0, < 2.2.1 | 2.2.1 |
| npm | jsonata | < 1.8.8 | 1.8.8 |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| jsonata-js | jsonata | < 1.8.8, >= 2.0.0, < 2.2.1 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_M | 4.0 | 9.3 Critical | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N |
| GitHub | 4.0 | 9.3 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Attack requirements: none
- Privileges required: none (no login)
- User interaction: none
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc, automatable yes, technical impact total.
- FIRST EPSS (model of 2026-10-21): 0.57% probability of exploitation activity in the next 30 days; percentile 46.
Timeline
- — CVE record published by GitHub_M
- — GitHub-reviewed advisory GHSA-2943-5xfg-gq5f published (critical)
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vulnerability records
- GitHub Advisory GHSA-2943-5xfg-gq5f github.com
- CVE.org record CVE-2026-77414 cve.org
- NVD entry CVE-2026-77414 nvd.nist.gov
Other references from the CVE record and advisory
- github.com github.com
- github.com github.com
- github.com github.com
- github.com github.com
- github.com github.com
- github.com github.com
- github.com github.com