Incorrect Calculation of Buffer Size Affecting openssl-static package, versions *


Severity

Recommended
low

Based on CentOS security rating.

Threat Intelligence

EPSS
0.1% (27th percentile)

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  • Snyk IDSNYK-CENTOS6-OPENSSLSTATIC-17309789
  • published11 Jun 2026
  • disclosed9 Jun 2026

Introduced: 9 Jun 2026

NewCVE-2026-9076  (opens in a new tab)
CWE-131  (opens in a new tab)

How to fix?

There is no fixed version for Centos:6 openssl-static.

NVD Description

Note: Versions mentioned in the description apply only to the upstream openssl-static package and not the openssl-static package as distributed by Centos. See How to fix? for Centos:6 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1