CVE-2026-63072 (GCVE-0-2026-63072)

Vulnerability from cvelistv5 – Published: 2026-08-25 12:59 – Updated: 2026-08-25 14:29
VLAI
Title
Heap Buffer Overflow in CMS Key Unwrapping
Summary
Issue summary: OpenSSL CMS decryption sizes the key-unwrap output buffer based on querying the unwrapped key size, but the AES-WRAP-PAD unwrap primitive can write and cleanse more bytes than that query reports, causing an 8-byte out-of-bounds heap write. Impact summary: An attacker who supplies a crafted CMS message can trigger a deterministic 8-byte out-of-bounds heap write when the victim decrypts it with CMS_decrypt(), corrupting the heap and typically resulting in a Denial of Service. CWE: CWE-787: Out-of-bounds Write Description: The key-wrap OID is potentially attacker-controlled on the wire. CMS unwrapping allows both id-aesNNN-wrap-pad and id-aesNNN-wrap ciphers. An attacker can take a legitimate message and change a single OID byte to select the padded variant while leaving the message otherwise valid. Since the unwrap key is derived from the recipient's private operation (ECDH key agreement or ML-KEM decapsulation), the RFC 5649 integrity check cannot pass, and the decryption fails with integrity failure. The write is a fixed-size (8-byte), fixed-value (zero) heap overflow immediately past the allocation, requires no special configuration, and is reachable from the public CMS_decrypt() function. The consequence is a heap corruption leading to a Denial of Service. The fix in the CMS code sizes the unwrap output buffer for the worst case so a failed unwrap cannot write past the allocation. FIPS impact: no As the CMS code lives outside the FIPS module boundary, no FIPS modules are affected by this CVE.
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: none Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-25 14:29 UTC
CWE
Assigner
openssl CNA under the mitre root
CNA scorecard B 78/100 over 43 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
OpenSSL OpenSSL Affected: 4.0.0 , < 4.0.2 (semver)
Affected: 3.6.0 , < 3.6.4 (semver)
Affected: 3.5.0 , < 3.5.8 (semver)
Affected: 3.4.0 , < 3.4.7 (semver)
Affected: 3.0.0 , < 3.0.22 (semver)
Affected: 1.1.1 , < 1.1.1zi (custom)
guessed Create a notification for this product.
Date Public
2026-08-25 11:36
Credits
Bhabani Sankar Das Filipe Casal(Trail of Bits) Daniel Kubec
Show details on NVD website
To clipboard 

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                  "lessThan": "1.1.1zi",
                  "status": "affected",
                  "version": "1.1.1",
                  "versionType": "custom"
                }
              ]
            }
          ],
          "credits": [
            {
              "lang": "en",
              "type": "reporter",
              "value": "Bhabani Sankar Das"
            },
            {
              "lang": "en",
              "type": "reporter",
              "value": "Filipe Casal(Trail of Bits)"
            },
            {
              "lang": "en",
              "type": "remediation developer",
              "value": "Daniel Kubec"
            }
          ],
          "datePublic": "2026-08-25T11:36:16.000Z",
          "descriptions": [
            {
              "lang": "en",
              "supportingMedia": [
                {
                  "base64": false,
                  "type": "text/html",
                  "value": "Issue summary: OpenSSL CMS decryption sizes the key-unwrap output buffer based\u003cbr\u003eon querying the unwrapped key size, but the AES-WRAP-PAD unwrap primitive\u003cbr\u003ecan write and cleanse more bytes than that query reports, causing an 8-byte\u003cbr\u003eout-of-bounds heap write.\u003cbr\u003e\u003cbr\u003eImpact summary: An attacker who supplies a crafted CMS message can trigger a\u003cbr\u003edeterministic 8-byte out-of-bounds heap write when the victim decrypts it\u003cbr\u003ewith CMS_decrypt(), corrupting the heap and typically resulting in a Denial\u003cbr\u003eof Service.\u003cbr\u003e\u003cbr\u003eCWE: CWE-787: Out-of-bounds Write\u003cbr\u003e\u003cbr\u003eDescription: The key-wrap OID is potentially attacker-controlled on the wire.\u003cbr\u003eCMS unwrapping allows both id-aesNNN-wrap-pad and id-aesNNN-wrap ciphers.\u003cbr\u003eAn attacker can take a legitimate message and change a single OID byte to\u003cbr\u003eselect the padded variant while leaving the message otherwise valid. Since\u003cbr\u003ethe unwrap key is derived from the recipient\u0027s private operation (ECDH key\u003cbr\u003eagreement or ML-KEM decapsulation), the RFC 5649 integrity check cannot\u003cbr\u003epass, and the decryption fails with integrity failure.\u003cbr\u003e\u003cbr\u003eThe write is a fixed-size (8-byte), fixed-value (zero) heap overflow\u003cbr\u003eimmediately past the allocation, requires no special configuration, and is\u003cbr\u003ereachable from the public CMS_decrypt() function. The consequence is\u003cbr\u003ea heap corruption leading to a Denial of Service. The fix in the CMS code\u003cbr\u003esizes the unwrap output buffer for the worst case so a failed unwrap cannot\u003cbr\u003ewrite past the allocation.\u003cbr\u003e\u003cbr\u003eFIPS impact: no\u003cbr\u003e\u003cbr\u003eAs the CMS code lives outside the FIPS module boundary, no FIPS\u003cbr\u003emodules are affected by this CVE."
                }
              ],
              "value": "Issue summary: OpenSSL CMS decryption sizes the key-unwrap output buffer based\non querying the unwrapped key size, but the AES-WRAP-PAD unwrap primitive\ncan write and cleanse more bytes than that query reports, causing an 8-byte\nout-of-bounds heap write.\n\nImpact summary: An attacker who supplies a crafted CMS message can trigger a\ndeterministic 8-byte out-of-bounds heap write when the victim decrypts it\nwith CMS_decrypt(), corrupting the heap and typically resulting in a Denial\nof Service.\n\nCWE: CWE-787: Out-of-bounds Write\n\nDescription: The key-wrap OID is potentially attacker-controlled on the wire.\nCMS unwrapping allows both id-aesNNN-wrap-pad and id-aesNNN-wrap ciphers.\nAn attacker can take a legitimate message and change a single OID byte to\nselect the padded variant while leaving the message otherwise valid. Since\nthe unwrap key is derived from the recipient\u0027s private operation (ECDH key\nagreement or ML-KEM decapsulation), the RFC 5649 integrity check cannot\npass, and the decryption fails with integrity failure.\n\nThe write is a fixed-size (8-byte), fixed-value (zero) heap overflow\nimmediately past the allocation, requires no special configuration, and is\nreachable from the public CMS_decrypt() function. The consequence is\na heap corruption leading to a Denial of Service. The fix in the CMS code\nsizes the unwrap output buffer for the worst case so a failed unwrap cannot\nwrite past the allocation.\n\nFIPS impact: no\n\nAs the CMS code lives outside the FIPS module boundary, no FIPS\nmodules are affected by this CVE."
            }
          ],
          "metrics": [
            {
              "format": "other",
              "other": {
                "content": {
                  "text": "Moderate"
                },
                "type": "https://openssl-library.org/policies/general/security-policy/"
              }
            }
          ],
          "problemTypes": [
            {
              "descriptions": [
                {
                  "cweId": "CWE-787",
                  "description": "CWE-787 Out-of-bounds Write",
                  "lang": "en",
                  "type": "CWE"
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-08-25T12:59:34.428Z",
            "orgId": "3a12439a-ef3a-4c79-92e6-6081a721f1e5",
            "shortName": "openssl"
          },
          "references": [
            {
              "name": "OpenSSL Advisory",
              "tags": [
                "vendor-advisory"
              ],
              "url": "https://openssl-library.org/news/secadv/20260825.txt"
            },
            {
              "name": "4.0.2 git commit",
              "tags": [
                "patch"
              ],
              "url": "https://github.com/openssl/openssl/commit/9530a5fd1aacaeccdced4478ea2340a480613335"
            },
            {
              "name": "3.6.4 git commit",
              "tags": [
                "patch"
              ],
              "url": "https://github.com/openssl/openssl/commit/2a3dac874c8057c1f0186849bf1ede1ae7b6b756"
            },
            {
              "name": "3.5.8 git commit",
              "tags": [
                "patch"
              ],
              "url": "https://github.com/openssl/openssl/commit/87784ad619af36b8807c2044b3940006fccc1e42"
            },
            {
              "name": "3.4.7 git commit",
              "tags": [
                "patch"
              ],
              "url": "https://github.com/openssl/openssl/commit/9ec2f6d2ae2bcad907cf7ee38584855bafe4979a"
            },
            {
              "name": "3.0.22 git commit",
              "tags": [
                "patch"
              ],
              "url": "https://github.com/openssl/openssl/commit/a0c8ec557d9cac078f032d76cdf684fe743eb382"
            }
          ],
          "source": {
            "discovery": "UNKNOWN"
          },
          "title": "Heap Buffer Overflow in CMS Key Unwrapping",
          "x_generator": {
            "engine": "Vulnogram 0.2.0"
          }
        }
      },
      "cveMetadata": {
        "assignerOrgId": "3a12439a-ef3a-4c79-92e6-6081a721f1e5",
        "assignerShortName": "openssl",
        "cveId": "CVE-2026-63072",
        "datePublished": "2026-08-25T12:59:34.428Z",
        "dateReserved": "2026-07-15T13:10:26.188Z",
        "dateUpdated": "2026-08-25T14:29:55.378Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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