CVE-2026-63072
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.
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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.
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Puntuación base: 7.5
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.92%
- Percentil entre todas las CVEs puntuadas: 59
- Fecha de la puntuación: 5/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1190Exploit Public-Facing Applicationinitial access85 % - Impacto principal
T1499.004Application or System Exploitationimpact90 %
Vector CVSS AV:N/AC:L/PR:N/UI:N indica explotación remota sin autenticación (T1190). CMS_decrypt() permite enviar mensaje CMS manipulado causando corrupción de heap y DoS determinístico (T1499.004: acceso a recursos).
Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.
🛡️ Mitigaciones ATT&CK que cubren estas técnicas
Tecnologías afectadas (1)
CWE
- CWE-787
Referencias
- https://github.com/openssl/openssl/commit/2a3dac874c8057c1f0186849bf1ede1ae7b6b756
- https://github.com/openssl/openssl/commit/87784ad619af36b8807c2044b3940006fccc1e42
- https://github.com/openssl/openssl/commit/9530a5fd1aacaeccdced4478ea2340a480613335
- https://github.com/openssl/openssl/commit/9ec2f6d2ae2bcad907cf7ee38584855bafe4979a
- https://github.com/openssl/openssl/commit/a0c8ec557d9cac078f032d76cdf684fe743eb382
- https://openssl-library.org/news/secadv/20260825.txt
JSON original (NVD)
Mostrar
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