Prototype pollution via overrideable forbidden-key check
Published Feb 21, 2026 · Updated Feb 21, 2026
Prototype pollution in NOLIMITS4WEB LLC Swiper 6.5.1 through 12.1.1 allows local users to modify Object.prototype via crafted input. The extend function in src/shared/utils.mjs filters forbidden keys with Array.prototype.indexOf, so an overridden indexOf returns -1 and admits a proto key. Exploitation requires attacker-controlled data to reach extendDefaults after Array.prototype.indexOf is overridden; downstream consequences depend on application sinks.
Summary
What happened
Prototype pollution in NOLIMITS4WEB LLC Swiper 6.5.1 through 12.1.1 allows local users to modify Object.prototype via crafted input. The extend function in src/shared/utils.mjs filters forbidden keys with Array.prototype.indexOf, so an overridden indexOf returns -1 and admits a proto key. Exploitation requires attacker-controlled data to reach extendDefaults after Array.prototype.indexOf is overridden; downstream consequences depend on application sinks.
The record
- CVE
- CVE-2026-27212
- Published
- Feb 21, 2026
- Updated
- Feb 21, 2026
- Vendor
- NOLIMITS4WEB LLC
- Product
- Swiper
- Classifications
- CWE-1321
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 21, 2026CVE publishedPublication date reported by the CVE source.
- Feb 21, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=>= 6.5.1, < 12.1.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
- Upstream Array.prototype.indexOf bypass proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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