---
title: "CVE-2026-27212: Prototype pollution in swiper"
url: https://erroneo.us/security/cve/CVE-2026-27212/
description: "CVE-2026-27212 (swiper (npm)): Swiper is a free and mobile touch slider with hardware accelerated transitions and native behavior. Versions 6.5.1 through…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-02-21
date_modified: 2026-02-24
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-27212"
kev: false
cvss: 9.4
epss: 0.0057
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-27212: Prototype pollution in swiper

**Signal:** Critical, preconditions apply. Severe if exploited, but exploitation needs conditions that may not apply to you. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.6% , percentile 46: FIRST’s model estimates a 0.6% chance of exploitation activity in the next 30 days, higher than 46% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Needs local access needed. Lower urgency for most teams unless an attacker could already run code on the machine.
- Only applies if your dependency tree includes swiper (npm) >= 6.5.1, < 12.1.2, fixed in 12.1.2 . Check your lockfile, including transitive dependencies.

## What it is

Swiper is a free and mobile touch slider with hardware accelerated transitions and native behavior. Versions 6.5.1 through 12.1.1 have a Prototype pollution vulnerability. The vulnerability resides in line 94 of shared/utils.mjs, where the indexOf() function is used to check whether user provided input contain forbidden strings. Despite a previous fix that attempted to mitigate prototype pollution by checking whether user input contained a forbidden key, it is still possible to pollute Object.prototype via a crafted input using Array.prototype. The exploit works across Windows and Linux and on Node and Bun runtimes. Any application that processes attacker-controlled input using this package may be affected by the following: Authentication Bypass, Denial of Service and RCE. This issue is fixed in version 12.1.2.

## Affected packages

- npm `swiper` >= 6.5.1, < 12.1.2 → fixed: 12.1.2

## Affected products (CVE record)

- nolimits4web swiper: >= 6.5.1, < 12.1.2

## Severity

- GitHub_M CVSS 4.0: 9.4 `CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`
- GitHub CVSS 4.0: 9.4 `CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.57% probability of exploitation activity in the next 30 days; percentile 46.

## Sources

- [GitHub Advisory GHSA-hmx5-qpq5-p643](https://github.com/advisories/GHSA-hmx5-qpq5-p643)
- [CVE.org record CVE-2026-27212](https://www.cve.org/CVERecord?id=CVE-2026-27212)
- [NVD entry CVE-2026-27212](https://nvd.nist.gov/vuln/detail/CVE-2026-27212)
- [github.com](https://github.com/nolimits4web/swiper/security/advisories/GHSA-hmx5-qpq5-p643)
- [github.com](https://github.com/nolimits4web/swiper/commit/d3e663322a13043ca63aaba235d8cf3900e0c8cf)
- [github.com](https://github.com/nolimits4web/swiper/releases/tag/v12.1.2)

---
Source page: https://erroneo.us/security/cve/CVE-2026-27212/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt