CVE-2026-123568 json
Sveltejs devalue before 5.6.3 Prototype Pollution via uneval Output
published 8mo ago modified 3d ago also EUVD-2026-119453 , GHSA-8qm3-746x-r74r
- cvss
- 4.4
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.2%
- EPSS 0.2% chance of exploitation in 30 days, percentile 10%
- public exploits
- 0
- none known
Summary
Sveltejs devalue before 5.6.3 contains a prototype pollution vulnerability that allows attackers to alter object prototypes by supplying untrusted data to uneval. When the generated code is later evaluated, it creates objects with polluted prototypes, producing output data whose shape differs from the original input.
Patch / fix
- npm devalue 5.6.3
- sveltejs devalue 5.6.3
Is CVE-2026-123568 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerExploit prediction
0.20% chance of exploitation in the next 30 days, higher than 10% of all scored CVEs (FIRST EPSS, 2026-11-11).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 2.1 | CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N |
| CNA | 3.1 | 4.4 | CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:N |
| CNA | 4.0 | 2.1 | CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
| NVD | 3.1 | 4.4 | CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| npm | devalue | <5.6.3 |
5.6.3 |
Affected products
- sveltejs devalue
Classification
- Weakness
-
- CWE-1321 Improperly Controlled Modification of Object Prototype Attributes
References
-
github.com
/sveltejs/devalue/commit/0f04d4d678eac39ad5d7a07d1956275d7874e81c
web
-
github.com
/sveltejs/devalue/security/advisories/GHSA-8qm3-746x-r74r
vendor-advisory, web, advisory
-
vulncheck.com
/advisories/sveltejs-devalue-before-5.6.3-prototype-pollution-via-uneval-output
third-party-advisory
-
github.com
/sveltejs/devalue
package
-
github.com
/sveltejs/devalue/releases/tag/v5.6.3
web
Sources
- CVE List CVE-2026-123568
- GitHub Advisory GHSA-8qm3-746x-r74r
- NVD CVE-2026-123568
- Maintainer advisory GHSA-8qm3-746x-r74r
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
The maintainers of sveltejs/devalue published their own advisory on GitHub. Reviewed sources take precedence over it.