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Fencer Vulns
high 7.5

CVE-2026-28388 json

NULL Pointer Dereference When Processing a Delta CRL

published 2026-04-07 7 mo ago modified 2026-10-15 25 d ago also EUVD-2026-19962 , JLSEC-2026-273

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.9%
EPSS 0.9% chance of exploitation in 30 days, percentile 60%
public exploits
0
none known

Summary

Issue summary: When a delta CRL that contains a Delta CRL Indicator extension is processed a NULL pointer dereference might happen if the required CRL Number extension is missing.

Impact summary: A NULL pointer dereference can trigger a crash which leads to a Denial of Service for an application.

When CRL processing and delta CRL processing is enabled during X.509 certificate verification, the delta CRL processing does not check whether the CRL Number extension is NULL before dereferencing it. When a malformed delta CRL file is being processed, this parameter can be NULL, causing a NULL pointer dereference.

Exploiting this issue requires the X509_V_FLAG_USE_DELTAS flag to be enabled in the verification context, the certificate being verified to contain a freshestCRL extension or the base CRL to have the EXFLAG_FRESHEST flag set, and an attacker to provide a malformed CRL to an application that processes it.

The vulnerability is limited to Denial of Service and cannot be escalated to achieve code execution or memory disclosure. For that reason the issue was assessed as Low severity according to our Security Policy.

The FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.

Patch / fix

  • julia AppBundler 1.0.1
  • julia OpenSSL_jll 3.0.20+0, 3.5.6+0
  • OpenSSL OpenSSL 1.0.2zp, 1.1.1zg, 3.0.20, 3.3.7, 3.4.5, 3.5.6, 3.6.2
  • Siemens SIMATIC CN 4100 V5.0
  • openssl Debian 12 3.0.19-1~deb12u2
  • openssl Debian 13 3.5.5-1~deb13u2
  • openssl Debian 14 3.6.2-1

debian advisories DEBIAN-CVE-2026-28388

  • openssl Ubuntu 22.04 LTS 3.0.2-0ubuntu1.23
  • openssl Ubuntu 24.04 LTS 3.0.13-0ubuntu3.9
  • openssl Ubuntu 25.10 3.5.3-1ubuntu3.3
  • openssl Ubuntu 26.10, Ubuntu 26.04 LTS 3.5.5-1ubuntu3
  • openssl Ubuntu Pro 14.04 LTS 1.0.1f-1ubuntu2.27+esm13
  • openssl Ubuntu Pro 16.04 LTS 1.0.2g-1ubuntu4.20+esm15
  • openssl Ubuntu Pro FIPS-updates 16.04 LTS 1.0.2g-1ubuntu4.fips.4.20.15
  • openssl Ubuntu Pro 18.04 LTS 1.1.1-1ubuntu2.1~18.04.23+esm8

ubuntu advisories UBUNTU-CVE-2026-28388

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • openssl hummingbird 1 3.5.6-0.1.hum1
  • openssl-libs hummingbird 1 3.5.6-0.1.hum1
  • openssl-perl hummingbird 1 3.5.6-0.1.hum1
  • openssl-config-fips hummingbird 1 3.5.6-0.1.hum1
  • openssl-devel-engine hummingbird 1 3.5.6-0.1.hum1

red hat advisories RHSA-2026:7261

  • openssl-1_0_0 SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +6 more 1.0.2p-150000.3.108.1
  • openssl-1_1 SLE Module for Legacy 15 SP7, SLE Module for Development Tools 15 SP7, SLE Module for Basesystem 15 SP7 1.1.1w-150700.11.16.1
  • openssl-3 SLE Module for Basesystem 15 SP7 3.2.3-150700.5.31.1
  • openssl-3 SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 3.5.0-160000.7.1
  • openssl-1_0_0 SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +7 more 1.0.2p-150000.3.105.1
  • openssl-1_1 SLES for SAP 15 SP5, SLES 15 SP5-LTSS, SLE Micro 5.5 +2 more 1.1.1l-150500.17.51.1
  • openssl-1_1 SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE Micro 5.4 +3 more 1.1.1l-150400.7.90.1
  • openssl-3 Linux Micro 6.0 3.1.4-12.1

suse advisories SUSE-SU-2026:2399-1SUSE-SU-2026:2396-1SUSE-SU-2026:1577-1SUSE-SU-2026:1386-1SUSE-SU-2026:1375-1SUSE-SU-2026:21107-1

  • openssl-3 openSUSE Leap 16.0 3.5.0-160000.7.1
  • openssl-3 openSUSE Tumbleweed 3.5.3-4.1

opensuse advisories openSUSE-SU-2026:20525-1openSUSE-SU-2026:10533-1

  • openssl Alpine 3.21, Alpine 3.20 3.3.7-r0
  • openssl Alpine 3.24, Alpine 3.23, Alpine 3.22 3.5.6-r0

alpine advisories ALPINE-CVE-2026-28388

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • openssl Azure Linux 3.0 3.3.5-5

azure linux advisories AZL-81953

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-28388 updated cvss 5.9

openssl: OpenSSL: Denial of Service due to NULL pointer dereference in delta CRL processing

  • Red Hat Enterprise Linux 6 openssl, openssl-perl Red Hat Enterprise Linux 7 ovmf, OVMF, AAVMF, openssl, openssl-libs, openssl-perl Red Hat Enterprise Linux 8 edk2, shim, openssl, shim-x64, edk2-ovmf, shim-aa64, +9 more Red Hat Enterprise Linux 9 edk2, shim, openssl, shim-x64, edk2-ovmf, shim-aa64, +7 more Red Hat Enterprise Linux 10 edk2, shim, openssl, shim-unsigned-x64, shim-unsigned-aarch64 Red Hat JBoss Core Services openssl
    +1 more products
    Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-core-bff-rhel9, rhoai/odh-dashboard-rhel9, rhoai/odh-mod-arch-maas-rhel9, rhoai/odh-mod-arch-automl-rhel9, rhoai/odh-mod-arch-gen-ai-rhel9, rhoai/odh-mod-arch-mlflow-rhel9, +6 more
    under investigation
  • Red Hat Hardened Images openssl 3.5.6-0.1.hum1, openssl-libs 3.5.6-0.1.hum1, openssl-perl 3.5.6-0.1.hum1, openssl-config-fips 3.5.6-0.1.hum1, openssl-devel-engine 3.5.6-0.1.hum1
    fixed: vendor fix RHSA-2026:7261
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-mlflow-rhel9, rhoai/odh-kube-rbac-proxy-rhel9, rhoai/odh-maas-controller-rhel9, rhoai/odh-mlflow-operator-rhel9, rhoai/odh-model-controller-rhel9, rhoai/odh-ogx-k8s-operator-rhel9, +14 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

cisa ICSA-26-293-05 updated cvss 7.5

Hitachi Energy RTU500 Product

  • Hitachi Energy RTU500 series CMU Firmware vers:RTU500_series_CMU_Firmware/>=13.5.1, <=13.5.4, vers:RTU500_series_CMU_Firmware/>=13.6.1, <=13.6.3, vers:RTU500_series_CMU_Firmware/>=13.7.1, <=13.7.8, vers:RTU500_series_CMU_Firmware/>=13.8.1, <=13.8.2
    affected: vendor fix, mitigation

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

cisa ICSA-24-102-01 updated cvss 7.5

Siemens SIMATIC S7-1500 TM MFP

  • Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
    affected: mitigation, no fix available

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
6 mo ago

Exploit prediction

0.92% chance of exploitation in the next 30 days, higher than 60% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
julia AppBundler
>=1.0.0, <1.0.1
1.0.1
julia OpenSSL_jll
<3.0.20+0
>=3.5.0+0, <3.5.6+0
3.0.20+0
3.5.6+0
julia Openresty_jll
all versions
 no fix listed

Affected products

  • OpenSSL OpenSSL
  • Siemens SIMATIC CN 4100
  • Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.