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Svelte CVE-2026-30226

HIGH
Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution) (CWE-1321)
2026-03-11 security-advisories@github.com GHSA-cfw5-2vxh-hr84
Denial Of Service Red Hat Prototype Pollution Devalue Svelte Suse
7.5
CVSS 3.1 · GitHub Advisory
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Craft malicious serialized payload
  2. Exploit
    Send to application using devalue.parse or devalue.unflatten
  3. Execution
    Pollute prototype chain
  4. Impact
    Trigger DoS or type confusion

Vulnerability Assessment

Weakness
CWE
CWE-1321
OWASP Top 10:2025
A03:2021 - Injection
ASVS 5.0
V3 - Web Frontend Security Prototype pollution prevention
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Initial Access

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

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Exploitation Conditions

Application must call devalue.parse() or devalue.unflatten() on untrusted input. Vulnerable in devalue versions 5.6.3 and earlier. No authentication required for remote exploitation.
Impact

Service disruption affecting availability. In critical infrastructure, DoS can have cascading effects on dependent systems.
Exploit ScenarioDerived

An attacker sends specially crafted requests that cause excessive resource consumption (CPU, memory, disk) or trigger a crash in the target application.
This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

In devalue v5.6.3, devalue.parse and devalue.unflatten were susceptible to prototype pollution via maliciously crafted payloads. Successful exploitation could lead to Denial of Service (DoS) or type confusion.

Earlier versions of this analysis (1)
v1 Mar 12, 2026 - 22:06 CVSS 7.5

RemediationAI

Implement rate limiting and input validation. Use timeout mechanisms for resource-intensive operations. Deploy DDoS protection where applicable.

Affected Packages

npm devalue fix: 5.6.4

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in npm

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

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Technical ContextAI · show details

A denial of service vulnerability allows an attacker to disrupt the normal functioning of a system, making it unavailable to legitimate users. This vulnerability is classified as Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution) (CWE-1321).

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  • Exploit and PoC references, threat intelligence from 22 sources
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Severity by source

GitHub Advisory PRIMARY 7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SUSE HIGH
Red Hat 5.9 MEDIUM

Primary rating from GitHub Advisory.

CVSS VectorGitHub Advisory

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

2
Patch released
Mar 31, 2026 - 21:13 nvd
Patch available
CVE Published
Mar 11, 2026 - 18:16 nvd
HIGH 7.5

DescriptionGitHub Advisory

Svelte devalue is a JavaScript library that serializes values into strings when JSON.stringify isn't sufficient for the job. In devalue v5.6.3 and earlier, devalue.parse and devalue.unflatten were susceptible to prototype pollution via maliciously crafted payloads. Successful exploitation could lead to Denial of Service (DoS) or type confusion. This vulnerability is fixed in 5.6.4.

Executive ViewAI

Why It Matters

Organizations using devalue face notable risk from CVE-2026-30226, a prototype pollution vulnerability rated CVSS 7.5. Exploitation could compromise the security of affected deployments. Organizations should apply vendor updates when available and consider compensating controls in the interim.

Business Impact: High
Compensating Controls

Apply vendor patch. If immediate patching is not feasible: (1) Implement network-level access controls to limit exposure; (2) Enable enhanced monitoring and alerting; (3) Apply principle of least privilege.

Threat Intelligence Overview

EPSS Score
0.0%
Top 87% exploitable
Data Quality
5 sources
Confidence: Medium
NVD CVE.org EPSS Vendor GitHub VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.0%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact
High

Priority Score

38
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +38
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Denial of Service MEDIUM

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

Affected Products (CPE)GitHub Advisory

cpe:2.3:a:svelte:devalue:*:*:*:*:*:node.js:*:*

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Vendor StatusVendor

SUSE

Severity: High
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Fixed
SUSE Linux Enterprise High Performance Computing 15 SP7 Fixed
SUSE Linux Enterprise Module for Python 3 15 SP7 Fixed
SUSE Linux Enterprise Server 15 SP7 Fixed
SUSE Linux Enterprise Server for SAP Applications 15 SP7 Fixed

References

Advisories & patches
ADVISORY https://vuldb.com/?id.350494 REF https://github.com/sveltejs/devalue/security/advisories/GHSA-cfw5-2vxh-hr84

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