CVE-2026-123564: sveltejs devalue · Unthrottled Resource Allocation
Affects sveltejs devalueSource CVE Database V5
Not known to be exploited · CVSS 8.7 High : upgrade to 5.9.3 soon.
Data as of 8 Nov 2026, 02:05 UTC
Thin evidence
One scorer or none| CNA (VulnCheck) | CVSS 4.0 | 8.7 |
|---|---|---|
| CNA (VulnCheck) | CVSS 3.1 | 7.5 |
- Patch
- Available – fixed in 5.9.3
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 8 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 7 Nov 2026.
What to do
Upgrade sveltejs devalue to 5.9.3.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| sveltejsdevalue | Affected
| Fixed in
|
npmdevaluepkg:npm/devalueOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Upgrade sveltejs devalue to version 5.9.3 or later, where this memory exhaustion vulnerability is fixed. No other mitigation or temporary workaround is indicated.
Description
CVE-2026-123564 is a high-severity memory exhaustion vulnerability in the sveltejs devalue library versions from 1.0.0 up to but not including 5.9.3. The flaw exists in the uneval function, which generates code for sparse arrays that allocates memory proportional to the array's declared length during evaluation. An attacker able to influence a very large sparse array serialized by an application can cause memory exhaustion in the browser or runtime environment. This issue is fixed in version 5.9.3.