VulnerabilityPublished 22 Apr 2026Updated 11 May 2026

CVE-2026-41691: i18next-http-backend has Path Traversal & URL Injection via Unsanitised lng/ns

Affects i18next-http-backendSource GCVE Database

Authoritative record:CVE-2026-41691· Medium 6.5

Not known to be exploited · CVSS 6.5 Medium : upgrade to 3.0.5 when convenient.

Data as of 27 Oct 2026, 01:27 UTC

CVSS 3.1 base score

6.5Medium

How severe the flaw is on the 0–10 CVSS scale.

Patch: Available – fixed in 3.0.5

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 7 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade i18next-http-backend to 3.0.5.

Affected software

Product	Affected	Fixed in
npmi18next-http-backend	Affected <3.0.5	Fixed in 3.0.5

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AI-suggested

Upgrade to i18next-http-backend version 3.0.5 or later, which includes fixes for URL path sanitization, per-instance fetch option handling, error message sanitization, and prototype pollution mitigation. If immediate upgrade is not possible, manually sanitize lng and ns inputs by stripping characters such as '..', '/', '\', '?', '#', '%', whitespace, and control characters, and limit their length before passing them to the library.

Description

Versions of i18next-http-backend prior to 3.0.5 improperly interpolate user-controlled language (lng) and namespace (ns) values into URL path templates without sanitization, enabling path traversal and URL injection. This can lead to unauthorized resource access or SSRF in certain configurations. Additional issues fixed in 3.0.5 include per-instance fetch option handling, log forging prevention, credential redaction in error messages, and prototype pollution mitigation.

Impact

An attacker able to influence the lng or ns parameters can manipulate the request URL to perform path traversal, query string injection, or fragment truncation. This may lead to unauthorized access to internal or filesystem resources, SSRF attacks, or bypass of path-based authorization controls. Additionally, prior to 3.0.5, a module-level flag could cause all backend instances to silently strip security-relevant fetch options, increasing risk. Log forging and credential leakage in error messages could also expose sensitive information or corrupt logs.

Summary

The i18next-http-backend library versions before 3.0.5 interpolate the lng and ns parameters directly into URL path templates without encoding or validation, allowing attackers who control these values to inject path traversal sequences (e.g., '../../config'), query strings, fragments, or URL-encoded bypasses. This can cause requests to access unintended resources or trigger SSRF when loadPath points to internal or file-scheme URLs. The 3.0.5 patch introduces strict URL segment validation rejecting unsafe characters and sequences, scopes fetch option omission per instance, sanitizes error messages to prevent log forging and credential leakage, and replaces unsafe prototype chain iteration with safer methods. The vulnerability is tracked as CVE-2026-41691 with a CVSS 3.1 score of 6.5 (medium severity).

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #6OWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Architecture and Design
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks…
Implementation · Input Validation
Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174).
OWASP Cheat Sheets
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V12.3.1 (opens in a new tab)
Attack patterns
Path Traversal (opens in a new tab)
Using Slashes and URL Encoding Combined to Bypass Validation Logic (opens in a new tab)
Manipulating Web Input to File System Calls (opens in a new tab)
Using Escaped Slashes in Alternate Encoding (opens in a new tab)
Using Slashes in Alternate Encoding (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection') (opens in a new tab)
Class weaknessLikelihood of exploit: HighOWASP Top 10 A05:2025: Injection (opens in a new tab)
The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
Requirements
Programming languages and supporting technologies might be chosen which are not subject to these issues.
Implementation
Utilize an appropriate mix of allowlist and denylist parsing to filter control-plane syntax from all input.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
Deserialization (opens in a new tab)
Injection Prevention (opens in a new tab)
SQL Injection Prevention (opens in a new tab)
Injection Prevention in Java (opens in a new tab)
OWASP ASVS 4.0.3
V1.5.1 (opens in a new tab)
Attack patterns
Buffer Overflow via Environment Variables (opens in a new tab)
Server Side Include (SSI) Injection (opens in a new tab)
HTTP Request Splitting (opens in a new tab)
Command Line Execution through SQL Injection (opens in a new tab)
Double Encoding (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 27 Oct 2026, 01:27 UTC

WeaknessesCWE-22, CWE-74

Technical details

References

Community reviews

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