vulnerability / NVI-00009055 / Revision 4
i18next-http-backend: Namespace value starting with / forms a protocol-relative URL when loadPath/addPath places {{ns}} right after a / (bypass of the // check added for GHSA-xvq9-wjp8-hwqf)
GitHub lists this reviewed advisory for i18next-http-backend. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
3.1 low
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
0.318%
FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.24815. Missing scores are unknown.
As of · FIRST EPSS
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
i18next-http-backend
source listed< 4.0.3
## Affected versions Verified on 4.0.2 (latest on npm) and on commit 07e0288 (the GHSA-xvq9-wjp8-hwqf fix). Earlier 3.x/4.x versions that allow `/` in ns are likely affected too. Not verified on them. ## Impact Same class as GHSA-xvq9-wjp8-hwqf and GHSA-q89c-q3h5-w34g: when an attacker controls the namespace value, the request goes to an attacker-chosen origin. In a browser this loads attacker-controlled translation JSON (content injection into the UI, and XSS where translations are rendered as HTML). The precondition is a template with `{{ns}}` right after a leading `/`, for example `/{{ns}}/{{lng}}.json`. The 4.0.2 maintainer note says templates with a leading `/` are safe. This case is outside that statement. ## Root cause `isSafeNsUrlSegment` rejects any ns containing `//`, but allows a single leading `/` (needed for nested namespaces like `a/b`). Interpolation into `/{{ns}}/...` puts the template's own `/` next to the value's `/`. The result starts with `//`, which is a protocol-relative URL. The check runs on the value, not on the final URL. ## Minimal PoC ```js import Backend from 'i18next-http-backend' const b = new Backend(null, { loadPath: '/{{ns}}/{{lng}}.json', req
i18next-http-backend
source listedSEMVER: introduced 0; fixed 4.0.3
## Affected versions Verified on 4.0.2 (latest on npm) and on commit 07e0288 (the GHSA-xvq9-wjp8-hwqf fix). Earlier 3.x/4.x versions that allow `/` in ns are likely affected too. Not verified on them. ## Impact Same class as GHSA-xvq9-wjp8-hwqf and GHSA-q89c-q3h5-w34g: when an attacker controls the namespace value, the request goes to an attacker-chosen origin. In a browser this loads attacker-controlled translation JSON (content injection into the UI, and XSS where translations are rendered as HTML). The precondition is a template with `{{ns}}` right after a leading `/`, for example `/{{ns}}/{{lng}}.json`. The 4.0.2 maintainer note says templates with a leading `/` are safe. This case is outside that statement. ## Root cause `isSafeNsUrlSegment` rejects any ns containing `//`, but allows a single leading `/` (needed for nested namespaces like `a/b`). Interpolation into `/{{ns}}/...` puts the template's own `/` next to the value's `/`. The result starts with `//`, which is a protocol-relative URL. The check runs on the value, not on the final URL. ## Minimal PoC ```js import Backend from 'i18next-http-backend' const b = new Backend(null, { loadPath: '/{{ns}}/{{lng}}.json', req
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. FIRST EPSS
- vendor patch
The original advisory lists fixed boundaries 4.0.3 for i18next-http-backend. Confirm the publisher’s latest guidance.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database via OSV
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-9jhj-wvmw-cfx5 ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
- GHSA-9jhj-wvmw-cfx5 ↗
GitHub Advisory Database via OSV · vendor advisory
Observed . GitHub-origin advisory, CC-BY-4.0; OSV is an aggregate copy, not independent corroboration.
- CVE-2026-115730 ↗
FIRST EPSS · official catalog
Observed . FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 4 ·
Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.
- Revision 3 ·
Source facts changed; compare the preserved prior revision.
- Revision 2 ·
Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.