CVE-2026-28388
NULL Pointer Dereference When Processing a Delta CRL
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.
INFO
Published Date :
April 7, 2026, 10:16 p.m.
Last Modified :
April 23, 2026, 3:40 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | ||||
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Ensure X.509 certificate verification contexts do not use X509_V_FLAG_USE_DELTAS.
- Update to a version of the software that addresses this vulnerability.
- Validate CRL data integrity before processing.
- Disable delta CRL processing if possible.
Public PoC/Exploit Available at Github
CVE-2026-28388 has a 3 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-28388.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-28388 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-28388
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
None
trivy-nginx-scan
All Public RunWhen Helm Charts - Managed by terraform
Shell Dockerfile Go Template
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-28388 vulnerability anywhere in the article.
-
TheCyberThrone
OpenSSL 3.6.2: The Moderate Severity Wave
OpenSSL 3.6.2 landed this week carrying eight CVE fixes, with the project rating the most severe issue as Moderate. On the surface, that sounds reassuring—no critical exploits, no ransomware-grade zer ... Read more
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CybersecurityNews
Multiple OpenSSL Vulnerabilities Exposes Sensitive Data in RSA KEM Handling
OpenSSL has released a broad April 2026 security update that fixes seven vulnerabilities across supported branches, led by CVE-2026-31790, a moderate-severity flaw in RSA KEM RSASVE encapsulation that ... Read more
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Help Net Security
OpenSSL 3.6.2 lands with eight CVE fixes
OpenSSL 3.6.2 patches eight CVEs across a range of components. The project rates the most severe issue in the release as Moderate. What got fixed The release fixes incorrect failure handling in RSA KE ... Read more
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Daily CyberSecurity
OpenSSL Issues Major Security Advisory: RSA and Memory Vulnerabilities Fixed
OpenSSL has released a comprehensive security advisory detailing seven vulnerabilities ranging from Moderate to Low severity. The report, dated April 7, 2026, highlights critical fixes for modern vers ... Read more
The following table lists the changes that have been made to the
CVE-2026-28388 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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Initial Analysis by [email protected]
Apr. 23, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CPE Configuration OR *cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:* versions from (including) 3.0.0 up to (excluding) 3.0.20 *cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:* versions from (including) 3.3.0 up to (excluding) 3.3.7 *cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:* versions from (including) 3.4.0 up to (excluding) 3.4.5 *cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:* versions from (including) 3.5.0 up to (excluding) 3.5.6 *cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:* versions from (including) 3.6.0 up to (excluding) 3.6.2 *cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:* versions from (including) 1.0.2 up to (excluding) 1.0.2zp *cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:* versions from (including) 1.1.1 up to (excluding) 1.1.1zg Added Reference Type OpenSSL Software Foundation: https://github.com/openssl/openssl/commit/59c3b3158553ab53275bbbccca5cb305d591cf2e Types: Patch Added Reference Type OpenSSL Software Foundation: https://github.com/openssl/openssl/commit/5a0b4930779cd2408880979db765db919da55139 Types: Patch Added Reference Type OpenSSL Software Foundation: https://github.com/openssl/openssl/commit/602542f2c0c2d5edb47128f93eac10b62aeeefb3 Types: Patch Added Reference Type OpenSSL Software Foundation: https://github.com/openssl/openssl/commit/a9d187dd1000130100fa7ab915f8513532cb3bb8 Types: Patch Added Reference Type OpenSSL Software Foundation: https://github.com/openssl/openssl/commit/d3a901e8d9f021f3e67d6cfbc12e768129862726 Types: Patch Added Reference Type OpenSSL Software Foundation: https://openssl-library.org/news/secadv/20260407.txt Types: Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Apr. 10, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H -
New CVE Received by [email protected]
Apr. 07, 2026
Action Type Old Value New Value Added 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. Added CWE CWE-476 Added Reference https://github.com/openssl/openssl/commit/59c3b3158553ab53275bbbccca5cb305d591cf2e Added Reference https://github.com/openssl/openssl/commit/5a0b4930779cd2408880979db765db919da55139 Added Reference https://github.com/openssl/openssl/commit/602542f2c0c2d5edb47128f93eac10b62aeeefb3 Added Reference https://github.com/openssl/openssl/commit/a9d187dd1000130100fa7ab915f8513532cb3bb8 Added Reference https://github.com/openssl/openssl/commit/d3a901e8d9f021f3e67d6cfbc12e768129862726 Added Reference https://openssl-library.org/news/secadv/20260407.txt