CVE-2026-22803
Published: 15 January 2026
Summary
CVE-2026-22803 is a high-severity Memory Allocation with Excessive Size Value (CWE-789) vulnerability in Svelte Kit. Its CVSS base score is 8.2 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 40.5th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SC-5 (Denial-of-service Protection) and SI-10 (Information Input Validation).
Deeper analysis
CVE-2026-22803 is a denial-of-service vulnerability in SvelteKit, a framework for building robust web applications using Svelte. It affects versions 2.49.0 through 2.49.4, where the experimental form remote function processes submitted form data in a binary format. A specially crafted payload can cause the server to allocate an excessive amount of memory, leading to memory exhaustion and service disruption. The issue is linked to CWE-789 (Uncontrolled Memory Allocation) and CWE-770 (Allocation of Resources Without Limits or Throttling), with a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
An unauthenticated attacker with network access can exploit this vulnerability by submitting a malicious payload to the affected form remote function endpoint. The attack requires low complexity and no user interaction, allowing remote exploitation over the network. Successful attacks result in high-impact availability impairment through server memory exhaustion, with no impact on confidentiality or integrity.
Mitigation is provided in SvelteKit version 2.49.5, which addresses the memory allocation flaw. Relevant resources include the fixing commit at https://github.com/sveltejs/kit/commit/8ed8155215b9a74012fecffb942ad9a793b274e5, the @sveltejs/adapter-node release at https://github.com/sveltejs/kit/releases/tag/@sveltejs%2Fadapter-node@5.5.1, and the security advisory at https://github.com/sveltejs/kit/security/advisories/GHSA-j2f3-wq62-6q46. Affected deployments should upgrade promptly to the patched version.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-2789
Vulnerability details
SvelteKit is a framework for rapidly developing robust, performant web applications using Svelte. From 2.49.0 to 2.49.4, the experimental form remote function uses a binary data format containing a representation of submitted form data. A specially-crafted payload can cause the…
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server to allocate a large amount of memory, causing DoS via memory exhaustion. This vulnerability is fixed in 2.49.5.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Direct mapping to application exploitation causing endpoint DoS via memory exhaustion in a web framework.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly remediates the uncontrolled memory allocation flaw in SvelteKit's form remote function by applying timely vendor patches such as version 2.49.5.
Implements denial-of-service protections like traffic throttling and resource limits to counter memory exhaustion from specially crafted form payloads.
Validates binary form data inputs to ensure consistency and reject crafted payloads that trigger excessive server memory allocation.