CVE-2026-123569 json
Devalue before 5.6.3 Denial of Service via Sparse Array Serialization
published 8mo ago modified yesterday also EUVD-2026-119454 , GHSA-33hq-fvwr-56pm
- cvss
- 7.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 28%
- public exploits
- 0
- none known
Summary
The devalue package for npm before 5.6.3 can consume excessive CPU and memory when serializing sparse arrays with uneval or stringify. An attacker who manages to get a sparse array created on the server, which mainstream wire formats do not allow, and serialized there can cause a denial of service.
Patch / fix
- npm devalue 5.6.3
- sveltejs devalue 5.6.3
Is CVE-2026-123569 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 FencerCISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
- Assessed
- yesterday
Exploit prediction
0.34% chance of exploitation in the next 30 days, higher than 28% of all scored CVEs (FIRST EPSS, 2026-11-11).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 8.7 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N |
| CNA | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| CNA | 4.0 | 8.7 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/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 |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| npm | devalue | <5.6.3 |
5.6.3 |
Affected products
- sveltejs devalue
Classification
- Weakness
-
- CWE-770 Allocation of Resources Without Limits or Throttling
References
-
github.com
/sveltejs/devalue/commit/819f1ac7475ab37547645cfb09bf2f678a799cf0
web
-
github.com
/sveltejs/devalue/security/advisories/GHSA-33hq-fvwr-56pm
vendor-advisory, web, advisory
-
vulncheck.com
/advisories/devalue-before-5.6.3-denial-of-service-via-sparse-array-serialization
third-party-advisory
-
github.com
/sveltejs/devalue
package
-
github.com
/sveltejs/devalue/releases/tag/v5.6.3
web
Sources
- CVE List CVE-2026-123569
- GitHub Advisory GHSA-33hq-fvwr-56pm
- NVD CVE-2026-123569
- Maintainer advisory GHSA-33hq-fvwr-56pm
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.