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← Actionable
Medium, CVSS 5.8amended

Coraza: Truncated multipart body bypasses MULTIPART_STRICT_ERROR (rule 200003) via silent io.ErrUnexpectedEOF handling

CVE-2026-41508GHSA-r3rm-qphw-hh76

What to do

Partial vendor fix. Follow the primary source's mitigation guidance and check back for a fix.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • Go github.com/corazawaf/coraza/v3

    Affected
    >= 3.4.0, <= 3.7.0
    Fixed in
    3.8.0

  • Go github.com/corazawaf/coraza

    Affected
    every version
    Fixed in
    no fixed version recorded

  • Go github.com/corazawaf/coraza/v2

    Affected
    every version
    Fixed in
    no fixed version recorded

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
5.8 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
EPSS
  • CVE-2026-41508: 0.50% estimated exploitation activity in the next 30 days; percentile 42.65 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Root Cause File: internal/bodyprocessors/multipart.go (since commit 3347961b, PR #1453 "feat: ignore unexpected EOF in MIME multipart request body processor", merged 2026-03-06, first shipped in v3.4.0). The multipart body processor treats io.ErrUnexpectedEOF as a benign condition. Three sites are affected; all mishandle the error the same way. File branch, filesystem-backed (lines 71–77) File branch, TinyGo path (lines 82–88) Field branch (lines 102–113) The function then returns nil at line 116 for any body that ended prematurely. Consequences: 1. MULTIPARTSTRICTERROR stays at its initial value 0. 2. REQBODYERROR is not propagated either (since ProcessRequest returns nil). 3. Neither of the two canonical defensive rules shipped in coraza.conf-recommended fires: All other error branches in the same function (lines 27, 48, 66, 84, 104) correctly set MULTIPARTSTRICTERROR before returning; this is an inconsistency introduced in #1453, not a systemic issue. Context — why the error is…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-r3rm-qphw-hh76

  2. Revision 2 · amended ·

    Amended from osv record GO-2026-6670

  3. Revision 1 · created ·

    Published from osv record GHSA-r3rm-qphw-hh76

Agent brief

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# Patch Next advisory brief: CVE-2026-41508

Advisory: Coraza: Truncated multipart body bypasses MULTIPART_STRICT_ERROR (rule 200003) via silent io.ErrUnexpectedEOF handling
IDs: CVE-2026-41508, GHSA-r3rm-qphw-hh76
Record: https://patchnext.com/advisories/cve-2026-41508 (revision 3, source checked 26 Oct 2026, 15:29 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Partial vendor fix; fixed versions by package: github.com/corazawaf/coraza/v3 3.8.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/corazawaf/coraza/v3: affected >= 3.4.0, <= 3.7.0; fixed in 3.8.0
- Go github.com/corazawaf/coraza: affected every version
- Go github.com/corazawaf/coraza/v2: affected every version

## Suggested inspection (read-only)
- Go github.com/corazawaf/coraza/v3: check the installed version with your package manager.
- Go github.com/corazawaf/coraza: check the installed version with your package manager.
- Go github.com/corazawaf/coraza/v2: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/corazawaf/coraza/v3, github.com/corazawaf/coraza, github.com/corazawaf/coraza/v2.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GO-2026-6670 (OSV record GO-2026-6670 lists affected ranges: Go github.com/corazawaf/coraza >=0; Go github.com/corazawaf/coraza/v2 >=0; Go github.com/corazawaf/coraza/v3 >=3.4.0 <3.8.0 (fixed))
- Verified: https://osv.dev/vulnerability/GHSA-r3rm-qphw-hh76 (OSV record GHSA-r3rm-qphw-hh76 lists affected ranges: Go github.com/corazawaf/coraza/v3 >=3.4.0 <3.8.0 (fixed))
- Verified: https://github.com/advisories/GHSA-r3rm-qphw-hh76 (GitHub-reviewed advisory GHSA-r3rm-qphw-hh76 lists affected ranges: Go github.com/corazawaf/coraza/v3 >=3.4.0 <=3.7.0)

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