CVE-2026-28388NULL Pointer Dereference When Processing a Delta CRL
Updated under an hour ago ()
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It affects OpenSSL and 2 other products. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 7.5 HIGH (v3.1, CISA ADP)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- CWE-476
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- openssl
- NVD analysis
- Modified
- Record last updated
- Oct 15, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
OpenSSL OpenSSL openssl:openssl (from the name) | from 3.6.0 before 3.6.2; from 3.5.0 before 3.5.6; from 3.4.0 before 3.4.5; from 3.3.0 before 3.3.7; from 3.0.0 before 3.0.20; from 1.1.1 before 1.1.1zg; from 1.0.2 before 1.0.2zp | CNA record |
Siemens SIMATIC CN 4100 siemens:simatic_cn_4100 (from the name) | before V5.0 | CISA ADP |
Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem siemens:simatic_s7_1500_tm_mfp_gnu_linux_subsystem (from the name) | all versions | CISA ADP |
openssl openssl openssl:openssl | from 1.0.2 before 1.0.2zp; from 1.1.1 before 1.1.1zg; from 3.0.0 before 3.0.20; from 3.3.0 before 3.3.7; from 3.4.0 before 3.4.5; from 3.5.0 before 3.5.6; from 3.6.0 before 3.6.2 | NVD |
References
- https://openssl-library.org/news/secadv/20260407.txtvendor-advisory
- https://github.com/openssl/openssl/commit/602542f2c0c2d5edb47128f93eac10b62aeeefb3patch
- https://github.com/openssl/openssl/commit/d3a901e8d9f021f3e67d6cfbc12e768129862726patch
- https://github.com/openssl/openssl/commit/a9d187dd1000130100fa7ab915f8513532cb3bb8patch
- https://github.com/openssl/openssl/commit/5a0b4930779cd2408880979db765db919da55139patch
- https://github.com/openssl/openssl/commit/59c3b3158553ab53275bbbccca5cb305d591cf2epatch
- https://cert-portal.siemens.com/productcert/html/ssa-032379.html
- https://cert-portal.siemens.com/productcert/html/ssa-265688.html
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.