Use After Free in OpenSSL
CVE-2026-45447
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.
Vulnerability class: Use-After-Free
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.040 (90.2th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 90th percentile — 90.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.036 · newest: 0.040 · change: +0.004
Affected products
- OpenSSL — versions 4.0.0, 3.6.0, 3.5.0
Weakness classification (CWE)
Public proof-of-concept exploits
References
- github.com/openssl/security/commit/3aad5eb7af4de4ee0633c30a8541a54d9bbde63c
- github.com/openssl/security/commit/7d4a980c62258c5910cc883936e0c8dbab4d75a8
- github.com/openssl/security/commit/9dfd688ad2290fc5075cacbc9bf0c9a93eefed54
- github.com/openssl/security/commit/a541ae8bfe849a30cc885e8780715c0f488e496c
- github.com/openssl/security/commit/c505d7559da5d5f9f2c3913c6883a5562ce7273e
- openssl-library.org/news/secadv/20260609.txt (vendor-advisory, Vendor Advisory)
- github.com/openssl/openssl/commit/3aad5eb7af4de4ee0633c30a8541a54d9bbde63c (Patch, patch)
- github.com/openssl/openssl/commit/7d4a980c62258c5910cc883936e0c8dbab4d75a8 (Patch, patch)
- github.com/openssl/openssl/commit/9dfd688ad2290fc5075cacbc9bf0c9a93eefed54 (Patch, patch)
- github.com/openssl/openssl/commit/a541ae8bfe849a30cc885e8780715c0f488e496c (Patch, patch)
Frequently asked questions
- What is CVE-2026-45447?
- CVE-2026-45447 is a high-severity vulnerability in OpenSSL, classified under Use After Free. CVSS score: 8.8/10. Published 2026-06-09.
- How severe is CVE-2026-45447?
- High severity. CVSS v3 base score is 8.8 out of 10.
- Is CVE-2026-45447 known to be exploited?
- 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.