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Usage of non-constant time base64 decoder could lead to leakage of secret key material

Type: advisorySources: OSV

Versions before 0.7.0 of vodozemac use a non-constant time base64 implementation for importing key material for Megolm group sessions and `PkDecryption` Ed25519 secret keys. This flaw might allow an attacker to infer some information about the secret key material through a side-channel attack. ## Impact The use of a non-constant time base64 implementation might allow an attacker to observe timing variations in the encoding and decoding operations of the secret key material. This could potentially provide insights into the underlying secret key material. The impact of this vulnerability is considered low because exploiting the attacker is required to have access to high precision timing measurements, as well as repeated access to the base64 encoding or decoding processes. Additionally, the estimated leakage amount is bounded and low according to the referenced paper[[1]]. [1]: https://arxiv.org/abs/2108.04600

Products
vodozemac
Affected versions
Not specified
Fixed versions
0.7.0
CVEs
CVE-2024-40640
Confirmed fixed CVEs
Not specified
Updated in this feed
30 Oct 2026, 08:43 UTC · Revision 1

Source evidence

Usage of non-constant time base64 decoder could lead to leakage of secret key material

core-osv · Original source

Published 17 Jul 2024, 12:00 UTC

Versions before 0.7.0 of vodozemac use a non-constant time base64 implementation for importing key material for Megolm group sessions and `PkDecryption` Ed25519 secret keys. This flaw might allow an attacker to infer some information about the secret key material through a side-channel attack. ## Impact The use of a non-constant time base64 implementation might allow an attacker to observe timing variations in the encoding and decoding operations of the secret key material. This could potentially provide insights into the underlying secret key material. The impact of this vulnerability is considered low because exploiting the attacker is required to have access to high precision timing measurements, as well as repeated access to the base64 encoding or decoding processes. Additionally, the estimated leakage amount is bounded and low according to the referenced paper[[1]]. [1]: https://arxiv.org/abs/2108.04600

osv:RUSTSEC-2024-0354

vodozemac

Fixed versions: 0.7.0

Complete source record
{
  "id": "b0a614e473915e1da7e18709625e46fdea88a1d790446838474ba6b7d596fefb",
  "url": "https://osv.dev/vulnerability/RUSTSEC-2024-0354",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Usage of non-constant time base64 decoder could lead to leakage of secret key material",
    "summary": "Versions before 0.7.0 of vodozemac use a non-constant time base64 implementation for importing key material for Megolm group sessions and `PkDecryption` Ed25519 secret keys. This flaw might allow an attacker to infer some information about the secret key material through a side-channel attack. ## Impact The use of a non-constant time base64 implementation might allow an attacker to observe timing variations in the encoding and decoding operations of the secret key material. This could potentially provide insights into the underlying secret key material. The impact of this vulnerability is considered low because exploiting the attacker is required to have access to high precision timing measurements, as well as repeated access to the base64 encoding or decoding processes. Additionally, the estimated leakage amount is bounded and low according to the referenced paper[[1]]. [1]: https://arxiv.org/abs/2108.04600",
    "evidence": "osv:RUSTSEC-2024-0354",
    "products": [
      {
        "name": {
          "value": "vodozemac",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "0.7.0",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "RUSTSEC-2024-0354",
      "aliases": [
        "CVE-2024-40640",
        "GHSA-j8cm-g7r6-hfpq",
        "RUSTSEC-2024-0354"
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0.0.0-0"
                },
                {
                  "fixed": "0.7.0"
                }
              ]
            }
          ],
          "package": {
            "name": "vodozemac",
            "purl": "pkg:cargo/vodozemac",
            "ecosystem": "crates.io"
          },
          "database_specific": {
            "cvss": null,
            "source": "https://github.com/rustsec/advisory-db/blob/osv/crates/RUSTSEC-2024-0354.json",
            "categories": [
              "crypto-failure",
              "memory-exposure"
            ],
            "informational": null
          },
          "ecosystem_specific": {
            "affects": {
              "os": [],
              "arch": [],
              "functions": []
            },
            "affected_functions": null
          }
        }
      ],
      "modified": "2026-10-12T18:00:07.418792131Z",
      "provider": "osv",
      "references": [
        "https://crates.io/crates/vodozemac",
        "https://rustsec.org/advisories/RUSTSEC-2024-0354.html",
        "https://github.com/matrix-org/vodozemac/commit/734b6c6948d4b2bdee3dd8b4efa591d93a61d272"
      ],
      "provider_metadata": {
        "license": "CC0-1.0"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2024-40640",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 306379,
  "published_at": "2024-07-17T12:00:00+00:00"
}