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Medium 2 vendors · 2 advisories

CVE-2026-28388: NULL Pointer Dereference When Processing a Delta CRL

CVE-2026-28388 key facts

CISA KEV
Not listed (catalogue checked )
Highest advisory rating
Medium
CVSS base score
5.9 (NetApp), 5.9 (Red Hat)
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H · base score 7.5, scored by CISA-ADPAttack vector: network. Attack complexity: low. Privileges required: none. User interaction: none. Scope: unchanged. Confidentiality impact: none. Integrity impact: none. Availability impact: high.
Weakness
  • CWE-476 NULL Pointer Dereference
EPSS
0.92% chance of exploitation in the next 30 days (60th percentile). FIRST EPSS, .
CISA SSVC
Exploitation: none observed. Automatable: yes. Technical impact: partial. CISA, .
Fixed releases
  • Red Hat: RHSA-2026:7261
Vendor advisories
2 from NetApp, Red Hat
Assigned by
openssl (CNA)
CVE record published
Listed by VulniPulse
Record changed

Ratings, versions and fixes are quoted from the vendor advisories that cover only CVE-2026-28388; each belongs to its advisory, not to every product listed. How records are collected and checked.

Description

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.

Text from the CVE.org record (openssl).

How do I fix CVE-2026-28388?

Upgrade to a fixed release named by the vendor:

  • Red Hat: RHSA-2026:7261
  • NetApp HCI Baseboard Management Controller (BMC) - H610S has no planned fix; migrate to a supported release or product and consult NetApp's end-of-support notice. (NetApp)
  • Update the affected package(s) to the fixed version shipped in RHSA-2026:7261 (`sudo dnf update` / `yum update`). (Red Hat)

Vendor advisories for CVE-2026-28388

NetApp

1 advisory
  • Advisory severityMedium5.9

    Medium [CVE-2026-28388] OpenSSL Vulnerability in NetApp Products

    NTAP-20260417-0014Source published Source updated

    Multiple NetApp products incorporate OpenSSL. Certain versions of OpenSSL are susceptible to a vulnerability which when successfully exploited could lead to Denial of Service (DoS). Successful exploitation of this vulnerability could lead to Denial of Service (DoS). Affected products: NetApp HCI Baseboard Management Controller (BMC) - H610S. NetApp reports that one or more additional products remain under investigation; review the canonical advisory for current status. NetApp states there is no workaround available at this time.

    Affected products in this advisory
    • NetApp HCI Baseboard Management Controller (BMC) - H610S
    Source-reported affected versions
    Affected-version details not available in this record.
    Source-reported fixed versions
    No fixed-version detail extracted. This does not mean no fix exists.
    Mitigation guidance
    • NetApp HCI Baseboard Management Controller (BMC) - H610S has no planned fix; migrate to a supported release or product and consult NetApp's end-of-support notice.
    Full advisory and evidenceOpen source bulletin

Red Hat

1 advisory
  • Advisory severityMedium5.9

    Medium [CVE-2026-28388] Denial of Service due to NULL pointer dereference in delta CRL processing

    CVE-2026-28388Source published

    Denial of Service due to NULL pointer dereference in delta CRL processing. Red Hat rates this low (CVSS 5.9). Weakness: CWE-476. Affected package(s): openssl-main. Resolved in Red Hat advisory RHSA-2026:7261 — update the affected packages (`sudo dnf update`).

    Related products — impact not confirmed
    • openssl-main
    • Red Hat Enterprise Linux
    Source-reported affected versions
    • openssl-main-3.5.6-0.1.hum1
    Source-reported fixed versions
    • RHSA-2026:7261
    Mitigation guidance
    • Update the affected package(s) to the fixed version shipped in RHSA-2026:7261 (`sudo dnf update` / `yum update`).
    Full advisory and evidenceOpen source bulletin

References

Timeline

  1. First vendor advisory listed by VulniPulse
  2. CVE record published
  3. CVE record last updated

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