Vulnerabilities in pkg:golang/github.com/gofiber/utils/v2

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-m98w-cqp3-qcqr",
  "modified" : "2025-12-12T16:30:26Z",
  "published" : "2025-12-08T17:57:26Z",
  "aliases" : [ "CVE-2025-66565" ],
  "summary" : "Fiber Utils UUIDv4 and UUID Silent Fallback to Predictable Values",
  "details" : "## Summary\n\nCritical security vulnerabilities exist in both the `UUIDv4()` and `UUID()` functions of the `github.com/gofiber/utils` package. When the system's cryptographic random number generator (`crypto/rand`) fails, both functions silently fall back to returning predictable UUID values, the zero UUID `\"00000000-0000-0000-0000-000000000000\"`. This compromises the security of all Fiber applications using these functions for security-critical operations on **Go versions prior to 1.24**.\n\n**Both functions are vulnerable to the same root cause (`crypto/rand` failure):**\n\n* `UUIDv4()`: Indirect vulnerability through `uuid.NewRandom()` → `crypto/rand.Read()` → fallback to `UUID()`\n* `UUID()`: Direct vulnerability through `crypto/rand.Read(uuidSeed[:])` → silent zero UUID return\n\n> **Note:** Go 1.24 and later panics on `crypto/rand` `Read()` failures, mitigating this vulnerability. Applications running on Go 1.24+ are not affected by the silent fallback behavior.\n\n---\n\n## Vulnerability Details\n\n### Affected Functions\n\n* **Package**: `github.com/gofiber/utils`\n* **Functions**: `UUIDv4()` and `UUID()`\n* **Return Type**: `string` (both functions)\n* **Locations**: `common.go:93-99` (UUIDv4), `common.go:60-89` (UUID)\n\n### Technical Description\n\nThe vulnerability occurs through two related but distinct failure paths, both ultimately caused by `crypto/rand.Read()` failures on Go < 1.24:\n\n#### Primary Path: UUIDv4() Vulnerability\n\n1. `UUIDv4()` calls `google/uuid.NewRandom()` which internally uses `crypto/rand.Read()`\n2. If `uuid.NewRandom()` fails, `UUIDv4()` falls back to the internal `UUID()` function\n3. **No error is returned to the application** - silent security failure occurs\n\n#### Secondary Path: UUID() Vulnerability\n\n1. `UUID()` directly calls `crypto/rand.Read(uuidSeed[:])` to seed its internal state\n2. If seeding fails, `UUID()` **silently fails** and returns the zero UUID `\"00000000-0000-0000-0000-000000000000\"`\n3. Applications receive predictable UUIDs with no indication of the security failure\n\n---\n\n### Code Analysis\n\n#### UUIDv4() Vulnerability Path\n\n```go\nfunc UUIDv4() string {\n\ttoken, err := uuid.NewRandom()  // Uses crypto/rand.Read() internally\n\tif err != nil {\n\t\treturn UUID()  // Dangerous fallback - no error returned to application\n\t}\n\treturn token.String()\n}\n```\n\n#### UUID() Vulnerability Path\n\n```go\nfunc UUID() string {\n\tuuidSetup.Do(func() {\n\t\tif _, err := rand.Read(uuidSeed[:]); err != nil {  // Direct crypto/rand.Read() call\n\t\t\treturn  // Silent failure - no seeding, uuidCounter remains 0\n\t\t}\n\t\tuuidCounter = binary.LittleEndian.Uint64(uuidSeed[:8])\n\t})\n\tif atomic.LoadUint64(&uuidCounter) <= 0 {\n\t\treturn \"00000000-0000-0000-0000-000000000000\"  // Zero UUID returned silently\n\t}\n\t// ... generate UUID from counter\n}\n```\n\n**Root Cause:** Both vulnerabilities stem from `crypto/rand.Read()` failures, occurring through different code paths with the same dangerous silent fallback behavior.\n\n---\n\n## Security Impact\n\n### Severity: CRITICAL\n\nThis issue is especially severe because many Fiber middleware packages (session, CSRF, auth, rate-limit, request-ID, etc.) default to `utils.UUIDv4()` for generating security-sensitive identifiers. A failure in `crypto/rand` would cause **every generated identifier across the entire application** to collapse to a single predictable value (the zero UUID), resulting in:\n\n* **Session fixation / universal session hijack**\n* **CSRF token predictability and bypass**\n* **Authentication token replay**\n* **Global identifier collisions leading to severe application breakage**\n* **Potential application-wide DoS** due to every request using the same “unique” key, causing cache overwrites, session stomping, corrupted internal maps, and loss of isolation across all users\n\n---\n\n### Attack Scenario\n\nWhile **entropy exhaustion is extremely rare on modern Linux systems**, *RNG access failures* (e.g., restricted `/dev/random` or `/dev/urandom` access, broken container environments, sandbox restrictions, misconfigured VMs, or FIPS-mode RNG failures) are realistic. In these scenarios on **Go < 1.24**, `crypto/rand` may return errors immediately — triggering the vulnerable fallback paths.\n\nOn **Go 1.24+**, `crypto/rand` `Read()` panics on failure, mitigating the silent-zero fallback issue.\n\n---\n\n### Proof of Concept\n\n1. `uuid.NewRandom()` fails (indirect `crypto/rand.Read()` failure)\n2. `UUIDv4()` calls `UUID()` as fallback with no error returned\n3. `UUID()` seeding fails directly via `crypto/rand.Read(uuidSeed[:])`\n4. Zero UUID `\"00000000-0000-0000-0000-000000000000\"` is returned silently\n5. No error is propagated to the application from either function\n\n---\n\n## Affected Versions\n\n* All versions of `github.com/gofiber/utils` containing the `UUIDv4()` or `UUID()` functions\n* Applications using Fiber middleware that depend on `UUIDv4()` or `UUID` for security\n* **Only applicable to Go < 1.24**; Go 1.24+ panics/block on `crypto/rand` `Read()` failures and is not affected\n\n---\n\n## Mitigation\n\n### Immediate Workaround\n\nReplace usage of `utils.UUIDv4()` with `uuid.New()` or wait for fix:\n\n```go\nsessionID := uuid.New()\n```\n\n### Recommended Fix\n\nModify `utils.UUIDv4()` and `utils.UUID()` to fail explicitly when cryptographic randomness is unavailable:\n\n```go\nfunc UUIDv4() string {\n\ttoken, err := uuid.NewRandom()\n\tif err != nil {\n\t\tpanic(fmt.Sprintf(\"utils: failed to generate secure UUID: %v\", err))\n\t}\n\treturn token.String()\n}\n\nfunc UUID() string {\n    uuidSetup.Do(func() {\n        if _, err := rand.Read(uuidSeed[:]); err != nil {\n            panic(fmt.Sprintf(\"utils: failed to seed UUID generator: %v\", err))\n        }\n        uuidCounter = binary.LittleEndian.Uint64(uuidSeed[:8])\n    })\n    if atomic.LoadUint64(&uuidCounter) <= 0 {\n        panic(\"utils: UUID generator not properly seeded\")\n    }\n    // ... generate UUID from counter\n}\n```\n\n---\n\n## Detection\n\nApplications can detect if they're affected by:\n\n1. Checking if they use `github.com/gofiber/utils`\n2. Searching for `UUIDv4()` and `UUID()` usage in security-critical code paths\n3. Reviewing Fiber middleware configurations that rely on defaults of `UUIDv4()` for security identifiers\n\n---\n\n## References\n\n* **Package Repository**: [https://github.com/gofiber/utils](https://github.com/gofiber/utils)\n* **Fiber Framework**: [https://github.com/gofiber/fiber](https://github.com/gofiber/fiber)\n* **Google UUID Library**: [https://github.com/google/uuid](https://github.com/google/uuid)\n* Golang `crypto/rand` behavior changes: [golang/go#66821](https://github.com/golang/go/issues/66821), [Go 1.25.5 source](https://cs.opensource.google/go/go/+/refs/tags/go1.25.5:src/crypto/rand/rand.go;l=80)\n\n---\n\n## Contact\n\nReported by: [@sixcolors](https://github.com/sixcolors)\n\n---\n\n## Classification\n\n* **OWASP**: A02:2021 - Cryptographic Failures\n* **Impact**: Complete compromise of application security model on Go < 1.24\n* **Exploitability**: Medium (requires entropy failure)\n* **Scope**: All Fiber applications using affected middleware on Go < 1.24",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/gofiber/utils/v2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.0.0-rc.4"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "< 2.0.0-rc.3.0.20251205210924-6c6cf047032b"
    }
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/gofiber/utils"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.2.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.1.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/gofiber/utils/security/advisories/GHSA-m98w-cqp3-qcqr"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-66565"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/gofiber/utils/commit/6c6cf047032b9c8dff43d29f990b4b10e9b02d47"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/gofiber/utils"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-252", "CWE-331", "CWE-338" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-12-08T17:57:26Z",
    "nvd_published_at" : "2025-12-09T16:18:21Z"
  }
}