Stack buffer overflow in PKCS7 SignedData encoding with custom signed attributes

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  "dataVersion": "5.2",
  "cveMetadata": {
    "cveId": "CVE-2026-0819",
    "assignerOrgId": "50d2cd11-d01a-48ed-9441-5bfce9d63b27",
    "assignerShortName": "wolfSSL",
    "dateUpdated": "2026-03-19T17:19:37.134Z",
    "dateReserved": "2026-01-09T17:04:43.340Z",
    "datePublished": "2026-03-19T16:54:33.442Z",
    "state": "PUBLISHED"
  },
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      "providerMetadata": {
        "orgId": "50d2cd11-d01a-48ed-9441-5bfce9d63b27",
        "shortName": "wolfSSL",
        "dateUpdated": "2026-03-19T16:54:33.442Z"
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      "title": "Stack buffer overflow in PKCS7 SignedData encoding with custom signed attributes",
      "descriptions": [
        {
          "lang": "en",
          "value": "A stack buffer overflow vulnerability exists in wolfSSL's PKCS7 SignedData encoding functionality. In wc_PKCS7_BuildSignedAttributes(), when adding custom signed attributes, the code passes an incorrect capacity value (esd->signedAttribsCount) to EncodeAttributes() instead of the remaining available space in the fixed-size signedAttribs[7] array. When an application sets pkcs7->signedAttribsSz to a value greater than MAX_SIGNED_ATTRIBS_SZ (default 7) minus the number of default attributes already added, EncodeAttributes() writes beyond the array bounds, causing stack memory corruption. In WOLFSSL_SMALL_STACK builds, this becomes heap corruption. Exploitation requires an application that allows untrusted input to control the signedAttribs array size when calling wc_PKCS7_EncodeSignedData() or related signing functions.",
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              "value": "<p>A stack buffer overflow vulnerability exists in wolfSSL's PKCS7 SignedData encoding functionality. In wc_PKCS7_BuildSignedAttributes(), when adding custom signed attributes, the code passes an incorrect capacity value (esd-&gt;signedAttribsCount) to EncodeAttributes() instead of the remaining available space in the fixed-size signedAttribs[7] array. When an application sets pkcs7-&gt;signedAttribsSz to a value greater than MAX_SIGNED_ATTRIBS_SZ (default 7) minus the number of default attributes already added, EncodeAttributes() writes beyond the array bounds, causing stack memory corruption. In WOLFSSL_SMALL_STACK builds, this becomes heap corruption. Exploitation requires an application that allows untrusted input to control the signedAttribs array size when calling wc_PKCS7_EncodeSignedData() or related signing functions.</p>"
            }
          ]
        }
      ],
      "affected": [
        {
          "vendor": "wolfSSL",
          "product": "wolfSSL",
          "modules": [
            "wolfcrypt PKCS7"
          ],
          "programFiles": [
            "wolfcrypt/src/pkcs7.c"
          ],
          "programRoutines": [
            {
              "name": "wc_PKCS7_EncodeSignedData()"
            }
          ],
          "repo": "https://github.com/wolfSSL/wolfssl",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "5.5.0",
              "status": "affected",
              "versionType": "semver",
              "lessThan": "5.9.0"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "lang": "en",
              "description": "CWE-121: Stack-based Buffer Overflow",
              "cweId": "CWE-121",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "lang": "en",
              "description": "CWE-787: Out-of-bounds Write",
              "cweId": "CWE-787",
              "type": "CWE"
            }
          ]
        }
      ],
      "references": [
        {
          "url": "https://github.com/wolfSSL/wolfssl/pull/9630",
          "name": "GitHub Pull Request"
        }
      ],
      "impacts": [
        {
          "descriptions": [
            {
              "lang": "en",
              "value": "Overflow Buffers"
            }
          ]
        }
      ],
      "metrics": [
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              "lang": "en",
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      "workarounds": [
        {
          "lang": "en",
          "value": "Ensure that applications using wolfSSL PKCS7 signing functionality validate and limit the number of custom signed attributes (signedAttribsSz) to no more than MAX_SIGNED_ATTRIBS_SZ (default 7) minus the number of default signed attributes enabled. Do not allow untrusted input to control the signedAttribs array or its size.",
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              "value": "<p>Ensure that applications using wolfSSL PKCS7 signing functionality validate and limit the number of custom signed attributes (signedAttribsSz) to no more than MAX_SIGNED_ATTRIBS_SZ (default 7) minus the number of default signed attributes enabled. Do not allow untrusted input to control the signedAttribs array or its size.</p>"
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      ],
      "solutions": [
        {
          "lang": "en",
          "value": "Update to the patched version of wolfSSL. The fix adds proper bounds checking in wc_PKCS7_BuildSignedAttributes() to validate that the number of custom signed attributes does not exceed the available space in the fixed-size signedAttribs array, returning BUFFER_E if the limit is exceeded.",
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              "value": "<p>Update to the patched version of wolfSSL. The fix adds proper bounds checking in wc_PKCS7_BuildSignedAttributes() to validate that the number of custom signed attributes does not exceed the available space in the fixed-size signedAttribs array, returning BUFFER_E if the limit is exceeded.</p>"
            }
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      "credits": [
        {
          "lang": "en",
          "value": "Maor Caplan",
          "type": "finder"
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          "dateUpdated": "2026-03-19T17:19:37.134Z"
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        "title": "CISA ADP Vulnrichment",
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