HighCVE-2026-116580

Lxsmnsyc Seroval: Deserialization of Untrusted Data (CVE-2026-116580)

Published 26.10.2026Last modified 26.10.2026Sources: OSV, Hersteller, CVE.org

What is affected, what to do

Update Lxsmnsyc Seroval to version 1.6.8.

Affected: Lxsmnsyc Seroval lt *..1.6.8
Fixed in: Lxsmnsyc Seroval 1.6.8

Not sure whether and how you are affected? Ask a question about this vulnerability

Metrics

7.3

Priority

XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

Source: Vendor (CNA), CVSS v3

7.3

CVSS v3

Severity High on the scale from 0 to 10.

Source: OSV, Hersteller, CVE.org

0.3 %

EPSS score

Low — model estimates < 1% exploitation likelihood.

Source: FIRST EPSS, percentile 27.7

Show all metrics

Severity: High
Priority (0–325) The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first? Read in glossary: 72.65 Methodology
Exploit maturity An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack. Read in glossary: no public PoC known
XIEM Effective CVSS XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command. Read in glossary: 7.3 Methodology
CVSS v3 CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions. Read in glossary: 7.3
EPSS score The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“. Read in glossary: 0.3 %; Low — model estimates < 1% exploitation likelihood.
EPSS percentile The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking. Read in glossary: 27.7; Elevated — this CVE ranks above at least 10% of all CVEs scored today.
KEV status The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching. Read in glossary: —
Published: 26.10.2026
CWE CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect. Read in glossary: CWE-502

Detection rules

No NEOSEC detection rule is available for this vulnerability yet.

Classification under NIS2 and CRA

Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

NIS2 NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management. Read in glossary: High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
CRA The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates. Read in glossary: From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001 ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security. Read in glossary: Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

Description

Summary

When fromJSON rebuilt an async iterator, it called on() on the iterator's source without checking that the source was a seroval stream. A crafted payload could pick another value as the source, such as a function returned by an application plugin. The deserializer then called that value's on method.

This is a variant of GHSA-mv8w-475r-vwqw. That fix covered the promise and stream control nodes but not the async iterator node.

Impact

An application that passes untrusted input to fromJSON with plugins that return callable values can have those callables invoked during deserialization. What this allows depends on what the plugin's values do.

Affected versions

Versions up to 1.6.3 accept any value as the source.
1.6.4 rejects the reported payload.
1.6.5 to 1.6.7 check the source by node type, which a payload can get around by reusing a node id.
All versions up to 1.6.7 should be treated as affected.

Patches

Fixed in seroval@1.6.8. Streams and sequences are now internal class instances. The deserializer checks the source value with instanceof, so plain data and plugin values are rejected no matter which node id they use.

Workarounds

Avoid plugins whose deserialize returns functions or objects with an on method when decoding untrusted input. Upgrading to 1.6.8 is recommended.

Source: OSV (Open Source Vulnerabilities), GitHub Security Advisories, cvelistv5, NVD (NIST)

Affected products

The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

Affected products
		Affected versions	Fixed in
lxsmnsyc	seroval	`< 1.6.8`	`1.6.8`
npm	seroval	`<= 1.6.7` `—`	`1.6.8` `1.6.8`

Vendors and products

Lxsmnsyc Seroval

Weakness classes (CWE)

CWE-502Deserialization of Untrusted Data
Base
The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.
Entry at MITRE CWE-502

References & sources

github.comlxsmnsyc/seroval/commit/3edc78b495ea0d6bd498143e5b3e56996607c5f2x_refsource_MISC, web
github.comlxsmnsyc/seroval/commit/50926b3ee198fb757e6ce3aa70efeed38d931c8dx_refsource_MISC, web
github.comlxsmnsyc/seroval/releases/tag/seroval@1.6.8x_refsource_MISC, web
github.comlxsmnsyc/seroval/security/advisories/GHSA-7rv5-mrxv-xcr9x_refsource_CONFIRM, web
NVD (NIST)vuln/detail/CVE-2026-116580advisory
github.comlxsmnsyc/serovalpackage

Changes to this CVE

Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

26.10.2026ReceivedGitHub

CVSS V3.1: AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Weakness type: CWE-502

Description added or changed

New references:

Show 8 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Description	added	—	Seroval facilitates JavaScript value stringification, including complex structures beyond JSON.stringify capabilities. Prior to 1.6.8, fromJSON rebuilds an AsyncIteratorFactoryInstance by calling source.on(listener) without requiring source to be a genuine internal stream. With untrusted Seroval input and an application plugin that returns a callable value or an object exposing an on method, a crafted node can reuse an identifier so the deserializer invokes the plugin-produced value. This is an incomplete-fix variant of CVE-2026-59940. The resulting confidentiality, integrity, or availability impact depends on the behavior exposed by the application plugin. This issue is fixed in version 1.6.8.
CVSS	added	—	AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Weakness type (CWE)	added	—	CWE-502
Affected versions (publisher)	added	—	New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/116xxx/CVE-2026-116580.json">CVE-2026-116580</a>
Reference	added	—	https://github.com/lxsmnsyc/seroval/commit/3edc78b495ea0d6bd498143e5b3e56996607c5f2
Reference	added	—	https://github.com/lxsmnsyc/seroval/commit/50926b3ee198fb757e6ce3aa70efeed38d931c8d
Reference	added	—	https://github.com/lxsmnsyc/seroval/releases/tag/seroval@1.6.8
Reference	added	—	https://github.com/lxsmnsyc/seroval/security/advisories/GHSA-7rv5-mrxv-xcr9

Source identifier: security-advisories@github.com

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