CVE-2026-27118Network attack vector

Sensitive-response disclosure via unrestricted ISR parameter

Published Feb 20, 2026 · Updated Feb 20, 2026

Cache poisoning in @sveltejs/adapter-vercel before 6.3.2 allows remote attackers to disclose authenticated users' cached responses. The adapter exposes an internal ISR query parameter on every route and treats attacker-selected requests as cacheable content. A victim must visit an attacker-controlled link while authenticated; Vercel's WAF protects deployed applications, limiting the reported impact to disclosure.

CVSS severity5.3
Medium
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cache poisoning in @sveltejs/adapter-vercel before 6.3.2 allows remote attackers to disclose authenticated users' cached responses. The adapter exposes an internal ISR query parameter on every route and treats attacker-selected requests as cacheable content. A victim must visit an attacker-controlled link while authenticated; Vercel's WAF protects deployed applications, limiting the reported impact to disclosure.

The record

CVE
CVE-2026-27118
Published
Feb 20, 2026
Updated
Feb 20, 2026
Vendor
Svelte
Product
SvelteKit
Classifications
CWE-346, CAPEC-141, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 6.3.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Svelte · SvelteKitversion=< 6.3.2

Published CVSS scores

5.3GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-346Origin Validation Error
CAPEC-141Cache Poisoning
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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