CVE-2026-45447 is a high-severity (CVSS 8.8) Use After Free vulnerability. A fix is available — see the affected versions and patch details below.
Heap Use-After-Free in the PKCS7_verify() Function
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-45447.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-45447 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,386 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
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.
Affected Products
opensslopensslDetection & mitigation playbook
VulnerabilityDetect
Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).
Fix
Upgrade the affected component to the fixed release for CVE-2026-45447, or apply your distribution's backported patch — distro builds are often patched at an older version number, so check your vendor's advisory rather than the upstream version alone.
Workarounds
Constrain what reaches the vulnerable code: limit the size and shape of untrusted input, isolate the affected component in a sandboxed or least-privileged process, and enable the platform's memory-safety mitigations (ASLR, stack protector, hardened allocator) so an out-of-bounds access is more likely to fail closed than to be exploitable.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This High severity heap use-after-free flaw in OpenSSL's PKCS7_verify() function can be triggered by processing a specially crafted PKCS#7 or S/MIME signed message. This could lead to application crashes, memory corruption, or potentially remote code execution, impacting services that handle such messages. The…
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.Source: Red Hat security advisory for CVE-2026-45447 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 10 | openssl-1:3.5.5-4.el10_2 | RHSA-2026:25237 |
| Red Hat Enterprise Linux 10.0 Extended Update Support | openssl-1:3.2.2-16.el10_0.7 | RHSA-2026:71542 |
| Red Hat Enterprise Linux 6 Extended Lifecycle Support - EXTENSION | openssl-0:1.0.1e-61.el6_10.1 | RHSA-2026:66524 |
| Red Hat Enterprise Linux 7 Extended Lifecycle Support | openssl-1:1.0.2k-26.el7_9.2 | RHSA-2026:58563 |
| Red Hat Enterprise Linux 8 | compat-openssl10-1:1.0.2o-4.el8_10.3 | RHSA-2026:36215 |
| Red Hat Enterprise Linux 8 | openssl-1:1.1.1k-16.el8_6 | RHSA-2026:26275 |
| Red Hat Enterprise Linux 8.8 Telecommunications Update Service | compat-openssl10-1:1.0.2o-4.el8_8.1 | RHSA-2026:36217 |
| Red Hat Enterprise Linux 9 | openssl-1:3.5.5-4.el9_8 | RHSA-2026:25239 |
Frequently Asked Questions
Is CVE-2026-45447 in your dependencies?
Find it across , including transitive dependencies.