Security readout for executives and security teams
Plain-English summary
CVE-2026-23737 affects the JavaScript package seroval. In vulnerable versions, unsafe JSON deserialization can let an attacker execute JavaScript if the application accepts and later processes crafted serialized data. The public record rates this high severity, but exploitation requires specific conditions and repeated interaction with the same function.
Executive priority
Treat this as a high-priority dependency remediation for applications that deserialize client-supplied data with seroval. Broad emergency response is not indicated by current sources because active exploitation is not reported and exploitation complexity is high. Prioritize internet-facing or multi-tenant services first.
Technical view
The issue is CWE-502 in seroval's JSON deserialization, affecting fromJSON and fromCrossJSON in client-to-server transmission scenarios. Sources describe arbitrary JavaScript execution through overridden constant value and error deserialization paths. The CVSS is 7.5 with high attack complexity, low privileges required, no user interaction, and high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is most likely in JavaScript applications that depend on seroval versions listed as affected and deserialize data received from clients using fromJSON or fromCrossJSON. Dependency-only presence may not be exploitable unless untrusted serialized input reaches these functions and influences later runtime processing.
Exploitation context
No source in the bundle states active exploitation, and it is not marked KEV. Sources say an attacker needs at least four separate requests on the same function and partial knowledge of how serialized data is used later, making exploitation conditional but potentially severe.
Researcher notes
The source bundle contains a version inconsistency: the description says versions 1.4.0 and below are affected and also says fixed in 1.4.0, while the affected range is listed as below 1.4.1. Validate against the GitHub advisory and commit before finalizing remediation policy.
Mitigation direction
- Inventory applications and services using the seroval package.
- Prioritize systems processing client-supplied serialized data with seroval.
- Update seroval according to the GitHub advisory and fix commit guidance.
- If version guidance conflicts, follow the latest upstream advisory before deployment.
- Reduce or block untrusted input reaching fromJSON and fromCrossJSON where feasible.
Validation and detection
- Check dependency manifests and lockfiles for seroval versions in the affected range.
- Review code paths using fromJSON or fromCrossJSON on client-controlled data.
- Confirm updated packages are deployed in built artifacts, not only source repositories.
- Validate that untrusted serialized input is rejected or isolated from runtime processing.
- Track the GitHub advisory for corrected version details or additional guidance.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-502: Code execution behavior lookup
Code execution and unsafe deserialization weaknesses often justify reviewing execution behavior and process telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-23737 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H1.65.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/lxsmnsyc/seroval/security/advisories/GHSA-3rxj-6cgf-8cfwCVE reference · x_refsource_CONFIRM
- https://github.com/lxsmnsyc/seroval/commit/ce9408ebc87312fcad345a73c172212f2a798060CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Deserialization of Untrusted Data
Deserialization of Untrusted Data represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.