CVE-2026-9076 (GCVE-0-2026-9076)

Vulnerability from cvelistv5 – Published: 2026-06-09 16:03 – Updated: 2026-06-10 07:47
VLAI
Title
Out-of-Bounds Read in CMS Password-Based Decryption
Summary
Issue summary: When CMS password-based decryption (RFC 3211 / PWRI key unwrap) processes attacker-supplied CMS data, an attacker-chosen stream-mode KEK cipher can trigger a heap out-of-bounds read in kek_unwrap_key(). Impact summary: A heap buffer over-read may trigger a crash which leads to Denial of Service for an application if the input buffer ends at a memory page boundary and the following page is unmapped. There is no information disclosure as the over-read bytes are not revealed to the attacker. The key unwrapping function performs a check-byte test as specified in the RFC that reads 7 bytes from a heap allocation that is based on the wrapped key length from the message. There is a minimum length check based on the block length of the wrapping cipher. However the cipher is selected from an OID carried in the attacker's PWRI keyEncryptionAlgorithm with no requirement that the cipher be a block cipher. When an attacker selects a stream-mode cipher the guard will be ineffective and the allocated buffer containing the unwrapped key can be too small to fit the check-bytes specified in the RFC and a buffer over-read can happen. Applications calling CMS_decrypt() or CMS_decrypt_set1_password() (equivalently openssl cms -decrypt -pwri_password ...) on untrusted CMS data are vulnerable to this issue. No password knowledge is required: the over-read happens during the unwrap attempt before any authentication succeeds. The over-read is limited to a few bytes and is not written to output, so there is no information disclosure. Triggering a crash requires the allocation to border unmapped memory, which is unlikely with the normal allocator. The FIPS modules are not affected by this issue.
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 (v2.0.3)
CWE
Assigner
References
Impacted products
Vendor Product Version
OpenSSL OpenSSL Affected: 4.0.0 , < 4.0.1 (semver)
Affected: 3.6.0 , < 3.6.3 (semver)
Affected: 3.5.0 , < 3.5.7 (semver)
Affected: 3.4.0 , < 3.4.6 (semver)
Affected: 3.0.0 , < 3.0.21 (semver)
Affected: 1.1.1 , < 1.1.1zh (custom)
Affected: 1.0.2 , < 1.0.2zq (custom)
Create a notification for this product.
Date Public
2026-06-09 14:00
Credits
Bhabani Sankar Das Haruki Oyama (Waseda University) Nikola Pajkovsky
Show details on NVD website
To clipboard 

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No password knowledge is required: the\\nover-read happens during the unwrap attempt before any authentication\\nsucceeds.\\n\\nThe over-read is limited to a few bytes and is not written to output, so\\nthere is no information disclosure. Triggering a crash requires the\\nallocation to border unmapped memory, which is unlikely with the normal\\nallocator.\\n\\nThe FIPS modules are not affected by this issue.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"Issue summary: When CMS password-based decryption (RFC 3211 / PWRI key unwrap)\u003cbr\u003eprocesses attacker-supplied CMS data, an attacker-chosen stream-mode KEK\u003cbr\u003ecipher can trigger a heap out-of-bounds read in kek_unwrap_key().\u003cbr\u003e\u003cbr\u003eImpact summary: A heap buffer over-read may trigger a crash which leads to\u003cbr\u003eDenial of Service for an application if the input buffer ends at a memory\u003cbr\u003epage boundary and the following page is unmapped. There is no information\u003cbr\u003edisclosure as the over-read bytes are not revealed to the attacker.\u003cbr\u003e\u003cbr\u003eThe key unwrapping function performs a check-byte test as specified in the\u003cbr\u003eRFC that reads 7 bytes from a heap allocation that is based on the wrapped\u003cbr\u003ekey length from the message. There is a minimum length check based on the\u003cbr\u003eblock length of the wrapping cipher. However the cipher is selected from\u003cbr\u003ean OID carried in the attacker\u0027s PWRI keyEncryptionAlgorithm with no\u003cbr\u003erequirement that the cipher be a block cipher. When an attacker selects\u003cbr\u003ea stream-mode cipher the guard will be ineffective and the allocated buffer\u003cbr\u003econtaining the unwrapped key can be too small to fit the check-bytes\u003cbr\u003especified in the RFC and a buffer over-read can happen.\u003cbr\u003e\u003cbr\u003eApplications calling CMS_decrypt() or CMS_decrypt_set1_password()\u003cbr\u003e(equivalently openssl cms -decrypt -pwri_password ...) on untrusted CMS\u003cbr\u003edata are vulnerable to this issue. No password knowledge is required: the\u003cbr\u003eover-read happens during the unwrap attempt before any authentication\u003cbr\u003esucceeds.\u003cbr\u003e\u003cbr\u003eThe over-read is limited to a few bytes and is not written to output, so\u003cbr\u003ethere is no information disclosure. Triggering a crash requires the\u003cbr\u003eallocation to border unmapped memory, which is unlikely with the normal\u003cbr\u003eallocator.\u003cbr\u003e\u003cbr\u003eThe FIPS modules are not affected by this issue.\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-125\", \"description\": \"CWE-125 Out-of-bounds Read\"}]}], \"providerMetadata\": {\"orgId\": \"3a12439a-ef3a-4c79-92e6-6081a721f1e5\", \"shortName\": \"openssl\", \"dateUpdated\": \"2026-06-10T07:47:51.139Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-9076\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-06-10T07:47:51.139Z\", \"dateReserved\": \"2026-05-20T12:43:37.677Z\", \"assignerOrgId\": \"3a12439a-ef3a-4c79-92e6-6081a721f1e5\", \"datePublished\": \"2026-06-09T16:03:16.306Z\", \"assignerShortName\": \"openssl\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.