Parameter smuggling in @hapi/content header parser allows upload-filter bypass via duplicate parameters

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

@hapi/content provided HTTP Content-* headers parsing. Prior to 6.0.2, Content.disposition() retained the last occurrence of each duplicate parameter while Content.type() retained the first occurrence of duplicate charset and boundary parameters, creating a parameter-smuggling primitive when another component in the request-processing chain resolves duplicates the opposite way. This can allow an upload filename allowlist bypass in headers such as Content-Disposition: form-data; name="file"; filename="safe.txt"; filename="shell.php". This issue is fixed in version 6.0.2.

Source published

17 Jul 2026 20:11:44 UTC

Source modified

21 Jul 2026 02:16:04 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · 7.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:H/SA:N

@hapi/content provided HTTP Content-* headers parsing. Prior to 6.0.2, Content.disposition() retained the last occurrence of each duplicate parameter while Content.type() retained the first occurrence of duplicate charset and boundary parameters, creating a parameter-smuggling primitive when another component in the request-processing chain resolves duplicates the opposite way. This can allow an upload filename allowlist bypass in headers such as Content-Disposition: form-data; name="file"; filename="safe.txt"; filename="shell.php". This issue is fixed in version 6.0.2.

Source published

17 Jul 2026 20:17:16 UTC

Source modified

24 Oct 2026 20:10:00 UTC

Observed here

25 Oct 2026 10:17:27 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 7.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

### Impact The two parsers resolved duplicates inconsistently and silently: - `Content.disposition()` retained the last occurrence of each parameter. - `Content.type()` retained the first occurrence of charset and boundary. Either behavior creates a parameter-smuggling primitive when another component in the request-processing chain (a WAF, reverse proxy, security filter, or alternate parser) resolves duplicates the opposite way. The primary attack vector is upload filename allowlist bypass: `Content-Disposition: form-data; name="file"; filename="safe.txt"; filename="shell.php"` ### Patches The issue has been patched in 6.0.2. ### Workarounds Pre or post validate headers looking for duplicates. ### Resources - [RFC 6266 §4.1 — Content-Disposition syntax](https://www.rfc-editor.org/rfc/rfc6266#section-4.1) - [RFC 7231 §3.1.1.1 — Content-Type syntax](https://www.rfc-editor.org/rfc/rfc7231#section-3.1.1.1) - [RFC 7230 §3.2.6 — token character set](https://www.rfc-editor.org/rfc/rfc7230#section-3.2.6)

Source published

27 May 2026 00:37:20 UTC

Source modified

10 Sep 2026 03:51:04 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:H/SA:N

Publisher rating · HIGH