rustsec-2026-0072
Vulnerability from osv_rustsec
Published
2026-02-04 12:00
Modified
2026-03-24 08:16
Summary
Missing Check for All-Zero X25519 Shared Secret
Details

Computing an X25519 shared secret with x25519_dalek::StaticSecret::diffie_hellman does not include the check that the key exchange was contributory, i.e. does not ensure on its own that the resulting shared secret is non-zero.

Impact

RFC 9180 mandates that implementations of HPKE must check for all zero Diffie-Hellman shared secrets and abort if so.

Applications using hpke-rs with the RustCryto provider would not perform this check allowing for non-contributive Diffie-Hellman shared secrets. Applications using hpke-rs with the libcrux provider are not affected.

Mitigation

Starting with version 0.6.0, an error will be returned when the computed Diffie-Hellman shared secret is all-zero.

References
To clipboard 

{
  "affected": [
    {
      "database_specific": {
        "categories": [],
        "cvss": null,
        "informational": null
      },
      "ecosystem_specific": {
        "affected_functions": null,
        "affects": {
          "arch": [],
          "functions": [
            "hpke_rs_rust_crypto::HpkeRustCrypto::dh"
          ],
          "os": []
        }
      },
      "package": {
        "ecosystem": "crates.io",
        "name": "hpke-rs-rust-crypto",
        "purl": "pkg:cargo/hpke-rs-rust-crypto"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.0.0-0"
            },
            {
              "fixed": "0.6.0"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "versions": []
    }
  ],
  "aliases": [
    "GHSA-g433-pq76-6cmf"
  ],
  "database_specific": {
    "license": "CC0-1.0"
  },
  "details": "Computing an X25519 shared secret with\n`x25519_dalek::StaticSecret::diffie_hellman` does not include the\ncheck that the key exchange was contributory, i.e. does not ensure on\nits own that the resulting shared secret is non-zero.\n\n## Impact\nRFC 9180 mandates that implementations of HPKE must check for all zero\nDiffie-Hellman shared secrets and abort if so.\n\nApplications using hpke-rs with the RustCryto provider would not\nperform this check allowing for non-contributive Diffie-Hellman shared\nsecrets. Applications using hpke-rs with the libcrux provider are not\naffected.\n\n## Mitigation\nStarting with version `0.6.0`, an error will be returned when\nthe computed Diffie-Hellman shared secret is all-zero.",
  "id": "RUSTSEC-2026-0072",
  "modified": "2026-03-24T08:16:07Z",
  "published": "2026-02-04T12:00:00Z",
  "references": [
    {
      "type": "PACKAGE",
      "url": "https://crates.io/crates/hpke-rs-rust-crypto"
    },
    {
      "type": "ADVISORY",
      "url": "https://rustsec.org/advisories/RUSTSEC-2026-0072.html"
    },
    {
      "type": "WEB",
      "url": "https://github.com/cryspen/hpke-rs/pull/124"
    }
  ],
  "related": [],
  "severity": [],
  "summary": "Missing Check for All-Zero X25519 Shared Secret"
}


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