How severe is CVE-2026-41885?

CVE-2026-41885 has a CVSS score of 6.5/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2026-41885?

CVE-2026-41885 affects the following packages: i18next-locize-backend (npm). Ecosystems affected: npm.

How do I fix CVE-2026-41885?

Update i18next-locize-backend to 9.0.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-41885 is resolved across your whole dependency graph.

How do I detect CVE-2026-41885 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for i18next-locize-backend, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-41885 if there is no patch (or I can't update yet)?

Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

Is CVE-2026-41885 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-41885 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-41885?

CVE-2026-41885 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 13th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-41885?

CVE-2026-41885 is classified as Path Traversal (CWE-22), CWE-74 (CWE-74). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2026-41885 published, and has it been updated?

CVE-2026-41885 was published on May 8, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

MEDIUM severity

CVE-2026-41885 — i18next-locize-backend

MEDIUMFix: locize/i18next-locize-backend@8f81ad4

CVE-2026-41885 is a medium-severity (CVSS 6.5) Path Traversal vulnerability in i18next-locize-backend. A fix is available for i18next-locize-backend — see the affected versions and patch details below.

Path traversal / URL injection via unsanitised lng/ns/projectId/version in i18next-locize-backend

Also known asGHSA-mgcp-mfp8-3q45

Published

May 8, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 26, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-41885.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk-0.11%

Lower risk than most CVEs13th percentile — riskier than 13% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

78other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

i18next-locize-backendnpm

85Kdownloads / week

Description

Summary

Versions of i18next-locize-backend prior to 9.0.2 interpolate lng, ns, projectId, and version directly into the configured loadPath / privatePath / addPath / updatePath / getLanguagesPath URL templates with no path-component validation and no encoding. When an application exposes any of these values to user-controlled input (?lng= / ?ns= query parameters via i18next-browser-languagedetector, cookies, request headers, or a URL-derived projectId), a crafted value can change the structure of the outgoing request URL.

Affected call sites in lib/index.js (pre-patch): the interpolate() helper is used at the five URL-build sites — _readAny/read (line 415 for private, 426 for public), getLanguages (lines 271 and 296), and writePage (lines 616 and 622) for the missing-key and update POST paths. The helper interpolate in lib/utils.js substitutes raw values with no encoding.

Impact

An attacker who can influence lng, ns, projectId, or version can:

Path traversal — lng = '../../admin' against https://api.locize.app/{{projectId}}/{{version}}/{{lng}}/{{ns}} changes the request URL path segment that reaches the locize CDN / API.
Query-string injection — lng = 'en?x=y' appends an attacker-chosen query to the URL.
Fragment truncation — lng = 'en#x' silently truncates the path in browser fetches.
URL-encoded bypass — lng = 'en%2F..' leverages server-side decoding to reintroduce /...

The worst-case concrete impact is loading an unintended translation resource (potentially causing wrong content to render) and, when a custom loadPath is configured against an internal / file-scheme URL, SSRF or arbitrary-file read on the host running the backend.

Additionally, the pre-patch interpolate() function read data[key] without excluding prototype-chain properties — under prototype-pollution conditions in the same process, that path could pull values from Object.prototype into the URL.

Related fixes shipped in 9.0.2

The defaults() helper replaces for...in iteration with Object.keys() plus an explicit prototype-key guard so a polluted Object.prototype cannot leak into the merged options object.
New utils.interpolateUrl / isSafeUrlSegment / sanitizeLogValue / redactUrlCredentials helpers mirror the pattern shipped in [email protected] (see its advisory GHSA-q89c-q3h5-w34g).

Affected versions

All versions of i18next-locize-backend prior to 9.0.2.

Patch

Fixed in 9.0.2. lib/index.js now uses interpolateUrl() at every URL-build site and returns an error callback (or silently drops the queued write for writePage) when any interpolated value fails the safety check. Legitimate i18next language-code shapes (BCP-47, en_US, zh-Hant-HK, my-custom.ns, +-joined multi-language values) all pass.

Workarounds

No workaround short of upgrading. If you cannot upgrade immediately, sanitise lng / ns / projectId / version at your application boundary before passing them through to i18next — reject values containing .., /, \, ?, #, %, whitespace, control characters, and cap the length.

Credits

Discovered via an internal security audit of the i18next / locize ecosystem.

References

CWE-22: Path Traversal
CWE-74: Injection
CWE-1321: Prototype Pollution (amplification path)
Related advisory in the same ecosystem: GHSA-q89c-q3h5-w34g (i18next-http-backend)

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`i18next-locize-backend`	all versions	9.0.2`npm install i18next-locize-backend@9.0.2`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for i18next-locize-backend, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update i18next-locize-backend to 9.0.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-41885 is resolved across your whole dependency graph.
Workarounds
Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

Frequently Asked Questions

### Summary Versions of `i18next-locize-backend` prior to 9.0.2 interpolate `lng`, `ns`, `projectId`, and `version` directly into the configured `loadPath` / `privatePath` / `addPath` / `updatePath` / `getLanguagesPath` URL templates with no path-component validation and no encoding. When an application exposes any of these values to user-controlled input (`?lng=` / `?ns=` query parameters via `i18next-browser-languagedetector`, cookies, request headers, or a URL-derived `projectId`), a crafted value can change the structure of the outgoing request URL. Affected call sites in `lib/index.js`