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Response snapshot Oct 27, 2026, 02:47 UTC

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VulnerabilityCVE-2026-41691

Copilot said: i18nextify is a JavaScript library that adds i18nextify is a JavaScript library that adds website internationalization via a script tag, without source code changes....

Copilot said: i18nextify is a JavaScript library that adds i18nextify is a JavaScript library that adds website internationalization via a script tag, without source code changes. Versions prior to 3.0.

At a glance

Exploited
Not known
Severity
6.5 Medium (CVSS 3.1)
Chance of exploitation
0.3% in the next 30 days
Sources
2 independent sources

What to do

Check the vendor advisory for affected versions and fixes.

Read NVD CVE-2026-41691 (opens a new tab)

What happened

Copilot said: i18nextify is a JavaScript library that adds i18nextify is a JavaScript library that adds website internationalization via a script tag, without source code changes. Versions prior to 3.0.5 interpolate the lng and ns values directly into the configured loadPath / addPath URL template without any encoding, validation, or path sanitisation.

When an application exposes the language-code selection to user-controlled input (the default — i18next-browser-languagedetector reads ?lng= query params, cookies, localStorage, and request headers), an attacker can inject characters that change the structure of the outgoing request URL. This is a single URL-injection vulnerability.

The attacker-controlled value is neutralised before it is used as part of an output URL string; the attack shape covers both path traversal and broader URL-structure injection — both are closed by the one interpolateUrl sanitisation fix. This issue has been fixed in version 3.0.5. If users cannot upgrade immediately, they can work around the issue by sanitising lng / ns before they reach i18next (strip .., /, \, ?

, #, %, whitespace, and control characters; cap the length).

Scores and how they were measured

CVSS base severity

6.5

Version 3.1As of

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

0.3%

Scored Percentile 24.0%

Model and measurement source (opens a new tab)

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    NVD CVE-2026-41691 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  2. Primary source

    Vendor advisory (via NVD references) (opens a new tab)

    The vendor advisory referenced by the CVE record, for affected versions and fixes.

    Published Date not suppliedChecked

  3. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  4. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  5. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  6. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-41691, scored 2026-10-26. This is a model estimate, not proof of exposure.

    Published Checked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 26). Copilot said: i18nextify is a JavaScript library that adds i18nextify is a JavaScript library that adds website internationalization via a script tag, without source code changes.... (CVE-2026-41691). https://kevwire.com/record/CVE-2026-41691

MLA

"Copilot said: i18nextify is a JavaScript library that adds i18nextify is a JavaScript library that adds website internationalization via a script tag, without source code changes.... (CVE-2026-41691)." KEVWire, 26 Oct. 2026, kevwire.com/record/CVE-2026-41691.

Chicago

KEVWire. "Copilot said: i18nextify is a JavaScript library that adds i18nextify is a JavaScript library that adds website internationalization via a script tag, without source code changes.... (CVE-2026-41691)." Last modified October 26, 2026. https://kevwire.com/record/CVE-2026-41691.

Evidence summary (plain text)

Copilot said: i18nextify is a JavaScript library that adds
i18nextify is a JavaScript library that adds website internationalization via a script tag, without source code changes.... (May 7, 2026).
Copilot said: i18nextify is a JavaScript library that adds
i18nextify is a JavaScript library that adds website internationalization via a script tag, without source code changes. Versions prior to 3.0.5 interpolate the lng and ns values directly into the configured loadPath / addPath URL template without any encoding, validation, or path sanitisation. When an application exposes the language-code selection to user-controlled input (the default — i18next-browser-languagedetector reads ?lng= query params, cookies, localStorage, and request headers), an attacker can inject characters that change the structure of the outgoing request URL. This is a single URL-injection vulnerability. The attacker-controlled value is neutralised before it is used as part of an output URL string; the attack shape covers both path traversal and broader URL-structure injection — both are closed by the one interpolateUrl sanitisation fix. This issue has been fixed in version 3.0.5. If users cannot upgrade immediately, they can work around the issue by sanitising lng / ns before they reach i18next (strip .., /, \, ?, #, %, whitespace, and control characters; cap the length).
CVSS 6.5 (version 3.1; evidence as of Oct 26, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-41691).
EPSS 0.3% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-41691&date=2026-10-26).
Sources:
NVD CVE-2026-41691: https://nvd.nist.gov/vuln/detail/CVE-2026-41691
Vendor advisory (via NVD references): https://github.com/i18next/i18next-http-backend/security/advisories/GHSA-q89c-q3h5-w34g
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-26T20:05:59.720Z&lastModEndDate=2026-10-26T21:35:56.549Z&resultsPerPage=500&startIndex=1500
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-26T19:31:27.927Z&lastModEndDate=2026-10-26T21:05:56.246Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-26T19:01:15.495Z&lastModEndDate=2026-10-26T20:30:55.133Z&resultsPerPage=500&startIndex=500
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-41691&date=2026-10-26
Record ID: CVE-2026-41691.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 27, 2026, 01:40 UTC. Ingestion is not an independent editorial investigation.

NVD status: Analyzed. Publication in the NVD is not evidence of exploitation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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Record details

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