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Public proof of conceptFix available

CVE-2026-45447

Heap Use-After-Free in the PKCS7_verify() Function

A public proof of concept exists; no exploitation attested.

  • Published2026-06-09
  • Fixed in3.6.3 · 3.5.7 · 3.4.6 · 3.0.21 · 1.1.1zh · 1.0.2zq
  • WeaknessCWE-416 · CWE-825

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2026-06-0917:17CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-45447?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-45447?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
OpenSSL
BranchAffectedFixed in
3.6≥ 3.6.0, < 3.6.33.6.3
3.5≥ 3.5.0, < 3.5.73.5.7
3.4≥ 3.4.0, < 3.4.63.4.6
3.0≥ 3.0.0, < 3.0.213.0.21
1.1≥ 1.1.1, < 1.1.1zh1.1.1zh
1.0≥ 1.0.2, < 1.0.2zq1.0.2zq
4.0= 4.0.0no fix published

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • compat-openssl10AlmaLinux:8all versions · fixed in 1:1.0.2o-4.el8_10.3
  • compat-openssl11AlmaLinux:9all versions · fixed in 1:1.1.1k-5.el9_8.4
  • opensslAlmaLinux:10all versions · fixed in 1:3.5.5-4.el10_2.alma.1and 3 other packages
  • opensslAlmaLinux:9all versions · fixed in 1:3.5.5-4.el9_8and 3 other packages
  • opensslAlmaLinux:8all versions · fixed in 1:1.1.1k-16.el8_6and 3 other packages

Vendor advisories

  • CVE-2026-45447 Red Hat Product Security569 products fixed · 1 known affected

    openssl: Heap Use-After-Free in OpenSSL PKCS7_verify()

    openshift/ose-rhel-coreos-9 as a component of Red Hat OpenShift Container Platform 4

  • RHSA-2026:84573 Red Hat Product Security40 products fixed

    Red Hat Security Advisory: openssl security update

  • RHSA-2026:84572 Red Hat Product Security30 products fixed

    Red Hat Security Advisory: openssl security update

  • RHSA-2026:83617 Red Hat Product Security39 products fixed

    Red Hat Security Advisory: openssl security update

  • RHSA-2026:82888 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: cert-manager Operator for Red Hat OpenShift 1.17.2

  • RHSA-2026:82857 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: cert-manager Operator for Red Hat OpenShift 1.18.2

36 more advisories

Full record on NVD

Fix

  1. Update OpenSSL to 3.6.3 · 3.5.7 · 3.4.6 · 3.0.21 · 1.1.1zh · 1.0.2zq
  2. Vendor fix Red Hat Product Security RHSA-2026:84573 · 40 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
  3. Vendor fix Red Hat Product Security RHSA-2026:82888 · 1 productBefore applying this update, make sure all previously released errata relevant to your system have been applied. The steps to apply the upgraded images are different depending on the installation plan approval policy you used when installing the cert-manager Operator for Red Hat OpenShift. - If t…
  4. Vendor fix Red Hat Product Security RHSA-2026:76956 · 1 productBefore applying the update, back up your existing Red Hat JBoss Web Server installation, including all applications and configuration files. The References section of this erratum contains a download link for the update. You must be logged in to download the update.
  5. Vendor fix Red Hat Product Security RHSA-2026:67551 · 3 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
  6. Vendor fix Red Hat Product Security RHSA-2026:59831 · 1 productFor OpenShift Container Platform 4.12 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.…
  7. Workaround from the vendor Red Hat Product Security RHSA-2026:84573 · 49 productsMitigation 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.

Advisories and patches

Detection

read 2026-10-23 19:25 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
2 repositories, unverifiedHORKimhab/CVE-2026-454470xBlackash/CVE-2026-45447
PoC-in-GitHub

Sources

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
2026-06-09
Last Modified
2026-09-18
NVD status
Modified
MSRC Title
Heap Use-After-Free in the PKCS7_verify() Function

Frequently asked questions

What is 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.

Is CVE-2026-45447 actively exploited?

Active exploitation of CVE-2026-45447 has not been confirmed. Its EPSS score was 4.0% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-45447?

CVE-2026-45447 has a CVSS v3 base score of 8.1 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.

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