MediumFix available

Coraza: Multipart filename* (RFC 5987) charset restriction lets a decoy filename bypass FILES-based rules

Type: advisorySources: OSV2 source records

## Summary Coraza extracts a multipart file upload's filename using Go's standard-library `mime.ParseMediaType`, which only decodes the RFC 5987/6266 extended `filename*` `Content-Disposition` parameter when its declared charset is exactly `us-ascii` or `utf-8`. Any other charset — including `iso-8859-1`, which RFC 5987 explicitly permits — is silently dropped by the stdlib, with no error and no fallback signal. This lets an attacker present one filename to Coraza and a different one to the backend application in the same request. ## Affected variables `FILES` (documented as *"the original filenames as submitted by the client in the multipart upload"*), `FILES_SIZES`, and the file-vs-field routing decision that determines whether a part is tracked as a file at all. `MULTIPART_FILENAME` is not affected. It is declared in Coraza but is not populated by any code path in the affected versions. ## Details `internal/bodyprocessors/multipart.go`'s `originFileName` calls `mime.ParseMediaType` on the raw `Content-Disposition` header and reads `dispositionParams["filename"]`, which then populates `FILES`/`FILES_SIZES` for parts recognized as file uploads. Per RFC 7578 §4.2 and RFC 6266, when both `filename` and `filename*` are present, `filename*` is authoritative. Go's `mime.ParseMediaType` implements this precedence internally (`decode2231Enc` in `mediatype.go`), but only for `filename*` values whose charset token is `us-ascii` or `utf-8`: ```go // mime/mediatype.go if charset != "us

Products: github.com/corazawaf/coraza, github.com/corazawaf/coraza/v2, github.com/corazawaf/coraza/v3
Affected versions: Not specified
Fixed versions: 3.8.1
CVEs: CVE-2026-114101
Confirmed fixed CVEs: Not specified
Updated in this feed: 31 Oct 2026, 14:08 UTC · Revision 2

Source evidence

Coraza: Multipart filename* (RFC 5987) charset restriction lets a decoy filename bypass FILES-based rules

core-osv · Original source

Published 8 Oct 2026, 17:51 UTC

osv:GHSA-3wr7-993q-jrff

github.com/corazawaf/coraza/v3

Fixed versions: 3.8.1

Complete source record

{
  "id": "ca62fe101455b131025fa9f08c2b3e803573d69b60bdbf5fb51c2dffde052b1f",
  "url": "https://osv.dev/vulnerability/GHSA-3wr7-993q-jrff",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Coraza: Multipart filename* (RFC 5987) charset restriction lets a decoy filename bypass FILES-based rules",
    "summary": "## Summary Coraza extracts a multipart file upload's filename using Go's standard-library `mime.ParseMediaType`, which only decodes the RFC 5987/6266 extended `filename*` `Content-Disposition` parameter when its declared charset is exactly `us-ascii` or `utf-8`. Any other charset — including `iso-8859-1`, which RFC 5987 explicitly permits — is silently dropped by the stdlib, with no error and no fallback signal. This lets an attacker present one filename to Coraza and a different one to the backend application in the same request. ## Affected variables `FILES` (documented as *\"the original filenames as submitted by the client in the multipart upload\"*), `FILES_SIZES`, and the file-vs-field routing decision that determines whether a part is tracked as a file at all. `MULTIPART_FILENAME` is not affected. It is declared in Coraza but is not populated by any code path in the affected versions. ## Details `internal/bodyprocessors/multipart.go`'s `originFileName` calls `mime.ParseMediaType` on the raw `Content-Disposition` header and reads `dispositionParams[\"filename\"]`, which then populates `FILES`/`FILES_SIZES` for parts recognized as file uploads. Per RFC 7578 §4.2 and RFC 6266, when both `filename` and `filename*` are present, `filename*` is authoritative. Go's `mime.ParseMediaType` implements this precedence internally (`decode2231Enc` in `mediatype.go`), but only for `filename*` values whose charset token is `us-ascii` or `utf-8`: ```go // mime/mediatype.go if charset != \"us",
    "evidence": "osv:GHSA-3wr7-993q-jrff",
    "products": [
      {
        "name": {
          "value": "github.com/corazawaf/coraza/v3",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "3.8.1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "GHSA-3wr7-993q-jrff",
      "aliases": [
        "CVE-2026-114101",
        "GHSA-3wr7-993q-jrff",
        "GO-2026-6691"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "3.8.1"
                }
              ]
            }
          ],
          "package": {
            "name": "github.com/corazawaf/coraza/v3",
            "purl": "pkg:golang/github.com/corazawaf/coraza/v3",
            "ecosystem": "Go"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-3wr7-993q-jrff/GHSA-3wr7-993q-jrff.json"
          }
        }
      ],
      "modified": "2026-10-21T10:57:00.041974308Z",
      "provider": "osv",
      "references": [
        "https://github.com/corazawaf/coraza/security/advisories/GHSA-3wr7-993q-jrff",
        "https://github.com/corazawaf/coraza/commit/5427c501b2fea6ae1305903efef01b3049224a58",
        "https://github.com/corazawaf/coraza/commit/b2a9264437116bdd98a86fe345b2aec1152d3d7c",
        "https://github.com/corazawaf/coraza/commit/cae3c7407e7b84372c207033de03f15f89bf351a",
        "https://github.com/corazawaf/coraza",
        "https://github.com/corazawaf/coraza/releases/tag/v3.8.1"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-20",
          "CWE-436"
        ],
        "severity": "MODERATE",
        "github_reviewed": true,
        "nvd_published_at": null,
        "github_reviewed_at": "2026-10-08T17:51:36Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-114101",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 392969,
  "published_at": "2026-10-08T17:51:36+00:00"
}

Coraza: Multipart filename* (RFC 5987) charset restriction lets a decoy filename bypass FILES-based rules in github.com/corazawaf/coraza

core-osv · Original source

Published 19 Oct 2026, 21:08 UTC

Coraza: Multipart filename* (RFC 5987) charset restriction lets a decoy filename bypass FILES-based rules in github.com/corazawaf/coraza

osv:GO-2026-6691

github.com/corazawaf/coraza

Fixed versions: Not specified

github.com/corazawaf/coraza/v2

Fixed versions: Not specified

github.com/corazawaf/coraza/v3

Fixed versions: 3.8.1

Complete source record

{
  "id": "9b71004126bd6b2df3b555d71c54d097fa135c485976b7166b53c1fa74b5abfe",
  "url": "https://osv.dev/vulnerability/GO-2026-6691",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Coraza: Multipart filename* (RFC 5987) charset restriction lets a decoy filename bypass FILES-based rules in github.com/corazawaf/coraza",
    "summary": "Coraza: Multipart filename* (RFC 5987) charset restriction lets a decoy filename bypass FILES-based rules in github.com/corazawaf/coraza",
    "evidence": "osv:GO-2026-6691",
    "products": [
      {
        "name": {
          "value": "github.com/corazawaf/coraza",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      },
      {
        "name": {
          "value": "github.com/corazawaf/coraza/v2",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      },
      {
        "name": {
          "value": "github.com/corazawaf/coraza/v3",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "3.8.1",
            "evidence": "/affected/2/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "GO-2026-6691",
      "aliases": [
        "CVE-2026-114101",
        "GHSA-3wr7-993q-jrff",
        "GO-2026-6691"
      ],
      "affected": [
        {
          "ranges": [
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              "events": [
                {
                  "introduced": "0"
                }
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          ],
          "package": {
            "name": "github.com/corazawaf/coraza",
            "purl": "pkg:golang/github.com/corazawaf/coraza",
            "ecosystem": "Go"
          },
          "database_specific": {
            "source": "https://vuln.go.dev/ID/GO-2026-6691.json"
          },
          "ecosystem_specific": {}
        },
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "github.com/corazawaf/coraza/v2",
            "purl": "pkg:golang/github.com/corazawaf/coraza/v2",
            "ecosystem": "Go"
          },
          "database_specific": {
            "source": "https://vuln.go.dev/ID/GO-2026-6691.json"
          },
          "ecosystem_specific": {}
        },
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "3.8.1"
                }
              ]
            }
          ],
          "package": {
            "name": "github.com/corazawaf/coraza/v3",
            "purl": "pkg:golang/github.com/corazawaf/coraza/v3",
            "ecosystem": "Go"
          },
          "database_specific": {
            "source": "https://vuln.go.dev/ID/GO-2026-6691.json"
          },
          "ecosystem_specific": {}
        }
      ],
      "modified": "2026-10-21T10:57:00.041974308Z",
      "provider": "osv",
      "references": [
        "https://github.com/corazawaf/coraza/security/advisories/GHSA-3wr7-993q-jrff",
        "https://github.com/corazawaf/coraza/commit/5427c501b2fea6ae1305903efef01b3049224a58",
        "https://github.com/corazawaf/coraza/commit/b2a9264437116bdd98a86fe345b2aec1152d3d7c",
        "https://github.com/corazawaf/coraza/commit/cae3c7407e7b84372c207033de03f15f89bf351a",
        "https://github.com/corazawaf/coraza/releases/tag/v3.8.1"
      ],
      "provider_metadata": {
        "url": "https://pkg.go.dev/vuln/GO-2026-6691",
        "review_status": "UNREVIEWED"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-114101",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 392970,
  "published_at": "2026-10-19T21:08:17+00:00"
}