CVE-2026-45447

Analyzed Analyzed - Analysis Complete

Use-After-Free in OpenSSL PKCS#7 Verification

Publication date: 2026-06-09

Last updated on: 2026-06-16

Assigner: OpenSSL Software Foundation

Description

Issue summary: A specially crafted PKCS#7 or S/MIME signed message could trigger a use-after-free during PKCS#7 signature verification. Impact summary: A use-after-free may result in process crashes, heap corruption, or potentially remote code execution. When processing a PKCS#7 or S/MIME signed message, if the SignedData digestAlgorithms field is present as an empty ASN.1 SET, OpenSSL may incorrectly free a caller-owned BIO during PKCS7_verify(). A subsequent use of the BIO by the calling application results in a use-after-free condition. In the common case this occurs when the application later calls BIO_free() on the BIO originally passed to PKCS7_verify(). Depending on allocator behavior and application-specific BIO usage patterns, this may result in a crash or other memory corruption. In some application contexts this may potentially be exploitable for remote code execution. Applications that process PKCS#7 or S/MIME signed messages using OpenSSL PKCS#7 APIs may be affected. Applications using the CMS APIs for this processing are not affected. The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-06-09

Last Modified

2026-06-16

Generated

2026-06-30

AI Q&A

2026-06-10

EPSS Evaluated

2026-06-28

NVD

CVE-2026-45447

EUVD

EUVD-2026-35491

Affected Vendors & Products

Vendor	Product	Version / Range
openssl	openssl	From 1.0.2 (inc) to 1.0.2zq (exc)
openssl	openssl	From 1.1.1 (inc) to 1.1.1zh (exc)
openssl	openssl	From 3.0.0 (inc) to 3.0.21 (exc)
openssl	openssl	From 3.4.0 (inc) to 3.4.6 (exc)
openssl	openssl	From 3.5.0 (inc) to 3.5.7 (exc)
openssl	openssl	From 3.6.0 (inc) to 3.6.3 (exc)
openssl	openssl	4.0.0

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-416	The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

Attack-Flow Graph

Compliance Impact

The provided information does not specify any direct impact of this vulnerability on compliance with common standards and regulations such as GDPR or HIPAA.

Executive Summary

This vulnerability occurs when OpenSSL processes a specially crafted PKCS#7 or S/MIME signed message. If the SignedData digestAlgorithms field is present as an empty ASN.1 SET, OpenSSL may incorrectly free a caller-owned BIO during the PKCS7_verify() function.

This incorrect freeing leads to a use-after-free condition, meaning the application might later use memory that has already been freed, causing instability.

In practical terms, this happens when the application calls BIO_free() on the BIO originally passed to PKCS7_verify(), which may cause crashes, heap corruption, or potentially allow remote code execution depending on how memory is managed.

Applications using OpenSSL PKCS#7 APIs for processing signed messages are affected, but those using CMS APIs or the OpenSSL FIPS modules are not.

Impact Analysis

The vulnerability can lead to process crashes and heap corruption, which can cause denial of service or instability in applications processing PKCS#7 or S/MIME signed messages.

More seriously, in some application contexts, this use-after-free condition may be exploited to achieve remote code execution, allowing an attacker to run arbitrary code on the affected system.

Mitigation Strategies

To mitigate this vulnerability, update OpenSSL to a version that includes the fix for the use-after-free issue in PKCS7_verify().

Applications that process PKCS#7 or S/MIME signed messages using OpenSSL PKCS#7 APIs should be updated to use the patched OpenSSL versions.

Note that applications using the CMS APIs for this processing are not affected.

Also, the FIPS modules in OpenSSL versions 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this issue.

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