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Vulnerabilities

Vulnerability · CVE-2026-123567

Sveltejs devalue's and emit objects with own properties

Published Mar 12, 2026 · catalog updated Nov 13, 2026 · Sveltejs devalue's and emit

Last checked Nov 14, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-123567. EPSS is 0.24%. Act only if a listed version of Sveltejs devalue's and emit is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Sveltejs devalue's and emit).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium6.3
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.24%
Remediation
Advisory link
Affected products
npm devalue

Sveltejs devalue before 5.6.4 contains a prototype injection vulnerability that allows attackers to inject __proto__ own properties into objects returned by devalue.parse and devalue.unflatten. Attackers can supply crafted serialized input that, when downstream code merges results via Object.assign, alters the target object's prototype.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • npm devalue4.0.0 → 5.6.4

How to fix CVE-2026-123567

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-123567. EPSS is 0.24%. Act only if a listed version of Sveltejs devalue's and emit is installed.

Which versions are affected?

Compare what you have installed with 4.0.0 → 5.6.4. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-1321: Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). EPSS 0.24%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 12, 2026 · GitHub Advisory Database

    Detected

    In some circumstances, and could emit objects with own properties. This in and of itself is not a security vulnerability (and is possible with, for example, as well), but it can result in prototype injection if _downstream_ code handles it incorrectly:

  2. Nov 8, 2026 · GitHub Advisory Database

    Fix available

    devalue fixed in 5.6.4

  3. Nov 8, 2026 · GitHub Advisory Database

    Fix available

    devalue fixed in 5.6.4

  4. Nov 8, 2026 · GitHub Advisory Database

    Updated

    In some circumstances, and could emit objects with own properties. This in and of itself is not a security vulnerability (and is possible with, for example, as well), but it can result in prototype injection if _downstream_ code handles it incorrectly:

  5. Nov 13, 2026 · NIST NVD

    Updated

    Sveltejs devalue before 5.6.4 contains a prototype injection vulnerability that allows attackers to inject __proto__ own properties into objects returned by devalue.parse and devalue.unflatten. Attackers can supply crafted serialized input that, when downstream code merges results via Object.assign, alters the target object's prototype.

Sources

  • CVE.orgVulnerability recordCVE-2026-123567

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-123567

    30-day exploitation probability 0.24%

    first.org
  • GitHub Advisory DatabasePackage advisoryGHSA-mwv9-gp5h-frr4

    GitHub Advisory Database record mirrored by OSV.

    github.com
  • NIST NVDVulnerability recordCVE-2026-123567

    Sveltejs devalue before 5.6.4 contains a prototype injection vulnerability that allows attackers to inject __proto__ own properties into objects returned by devalue.parse and devalue.unflatten. Attackers can supply crafted serialized input that, when downstream code merges result

    nvd.nist.gov
  • OpenSSF OSV / OSV ScannerPackage advisoryGHSA-mwv9-gp5h-frr4

    Sveltejs devalue's and emit objects with own properties

    osv.dev

References

Freshness

Last verified in this catalog Nov 14, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSNov 14, 2026
  • NIST NVDNov 13, 2026
  • GitHub Advisory DatabaseNov 9, 2026
  • OpenSSF OSV / OSV ScannerNov 9, 2026
  • CVE.orgNov 8, 2026