CVE-2026-28388 (GCVE-0-2026-28388)

Vulnerability from cvelistv5 – Published: 2026-04-07 22:00 – Updated: 2026-05-12 12:08
VLAI
Title
NULL Pointer Dereference When Processing a Delta CRL
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.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: none Automatable: yes Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
  • CWE-476 - NULL Pointer Dereference
Assigner
References
Impacted products
Vendor Product Version
OpenSSL OpenSSL Affected: 3.6.0 , < 3.6.2 (semver)
Affected: 3.5.0 , < 3.5.6 (semver)
Affected: 3.4.0 , < 3.4.5 (semver)
Affected: 3.3.0 , < 3.3.7 (semver)
Affected: 3.0.0 , < 3.0.20 (semver)
Affected: 1.1.1 , < 1.1.1zg (custom)
Affected: 1.0.2 , < 1.0.2zp (custom)
Create a notification for this product.
Siemens SIMATIC CN 4100 Affected: 0 , < V5.0 (custom)
Create a notification for this product.
Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem Affected: 0 , < * (custom)
Create a notification for this product.
Date Public
2026-04-07 14:00
Credits
Igor Morgenstern (Aisle Research) Igor Morgenstern (Aisle Research)
Show details on NVD website
To clipboard 

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      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 7.5, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"HIGH\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\", \"integrityImpact\": \"NONE\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"HIGH\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"NONE\"}}, {\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-28388\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-04-10T20:18:04.195701Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-04-10T20:18:34.089Z\"}}], \"cna\": {\"title\": \"NULL Pointer Dereference When Processing a Delta CRL\", \"source\": {\"discovery\": \"UNKNOWN\"}, \"credits\": [{\"lang\": \"en\", \"type\": \"reporter\", \"value\": \"Igor Morgenstern (Aisle Research)\"}, {\"lang\": \"en\", \"type\": \"remediation developer\", \"value\": \"Igor Morgenstern (Aisle Research)\"}], \"metrics\": [{\"other\": {\"type\": \"https://openssl-library.org/policies/general/security-policy/\", \"content\": {\"text\": \"Low\"}}, \"format\": \"other\"}], \"affected\": [{\"vendor\": \"OpenSSL\", \"product\": \"OpenSSL\", \"versions\": [{\"status\": \"affected\", \"version\": \"3.6.0\", \"lessThan\": \"3.6.2\", \"versionType\": \"semver\"}, {\"status\": \"affected\", \"version\": \"3.5.0\", \"lessThan\": \"3.5.6\", \"versionType\": \"semver\"}, {\"status\": \"affected\", \"version\": \"3.4.0\", \"lessThan\": \"3.4.5\", \"versionType\": \"semver\"}, {\"status\": \"affected\", \"version\": \"3.3.0\", \"lessThan\": \"3.3.7\", \"versionType\": \"semver\"}, {\"status\": \"affected\", \"version\": \"3.0.0\", \"lessThan\": \"3.0.20\", \"versionType\": \"semver\"}, {\"status\": \"affected\", \"version\": \"1.1.1\", \"lessThan\": \"1.1.1zg\", \"versionType\": \"custom\"}, {\"status\": \"affected\", \"version\": \"1.0.2\", \"lessThan\": \"1.0.2zp\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unaffected\"}], \"datePublic\": \"2026-04-07T14:00:00.000Z\", \"references\": [{\"url\": \"https://openssl-library.org/news/secadv/20260407.txt\", \"name\": \"OpenSSL Advisory\", \"tags\": [\"vendor-advisory\"]}, {\"url\": \"https://github.com/openssl/openssl/commit/602542f2c0c2d5edb47128f93eac10b62aeeefb3\", \"name\": \"3.6.2 git commit\", \"tags\": [\"patch\"]}, {\"url\": \"https://github.com/openssl/openssl/commit/d3a901e8d9f021f3e67d6cfbc12e768129862726\", \"name\": \"3.5.6 git commit\", \"tags\": [\"patch\"]}, {\"url\": \"https://github.com/openssl/openssl/commit/a9d187dd1000130100fa7ab915f8513532cb3bb8\", \"name\": \"3.4.5 git commit\", \"tags\": [\"patch\"]}, {\"url\": \"https://github.com/openssl/openssl/commit/5a0b4930779cd2408880979db765db919da55139\", \"name\": \"3.3.7 git commit\", \"tags\": [\"patch\"]}, {\"url\": \"https://github.com/openssl/openssl/commit/59c3b3158553ab53275bbbccca5cb305d591cf2e\", \"name\": \"3.0.20 git commit\", \"tags\": [\"patch\"]}], \"x_generator\": {\"engine\": \"Vulnogram 0.2.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"Issue summary: When a delta CRL that contains a Delta CRL Indicator extension\\nis processed a NULL pointer dereference might happen if the required CRL\\nNumber extension is missing.\\n\\nImpact summary: A NULL pointer dereference can trigger a crash which\\nleads to a Denial of Service for an application.\\n\\nWhen CRL processing and delta CRL processing is enabled during X.509\\ncertificate verification, the delta CRL processing does not check\\nwhether the CRL Number extension is NULL before dereferencing it.\\nWhen a malformed delta CRL file is being processed, this parameter\\ncan be NULL, causing a NULL pointer dereference.\\n\\nExploiting this issue requires the X509_V_FLAG_USE_DELTAS flag to be enabled in\\nthe verification context, the certificate being verified to contain a\\nfreshestCRL extension or the base CRL to have the EXFLAG_FRESHEST flag set, and\\nan attacker to provide a malformed CRL to an application that processes it.\\n\\nThe vulnerability is limited to Denial of Service and cannot be escalated to\\nachieve code execution or memory disclosure. For that reason the issue was\\nassessed as Low severity according to our Security Policy.\\n\\nThe FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this issue,\\nas the affected code is outside the OpenSSL FIPS module boundary.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"Issue summary: When a delta CRL that contains a Delta CRL Indicator extension\u003cbr\u003eis processed a NULL pointer dereference might happen if the required CRL\u003cbr\u003eNumber extension is missing.\u003cbr\u003e\u003cbr\u003eImpact summary: A NULL pointer dereference can trigger a crash which\u003cbr\u003eleads to a Denial of Service for an application.\u003cbr\u003e\u003cbr\u003eWhen CRL processing and delta CRL processing is enabled during X.509\u003cbr\u003ecertificate verification, the delta CRL processing does not check\u003cbr\u003ewhether the CRL Number extension is NULL before dereferencing it.\u003cbr\u003eWhen a malformed delta CRL file is being processed, this parameter\u003cbr\u003ecan be NULL, causing a NULL pointer dereference.\u003cbr\u003e\u003cbr\u003eExploiting this issue requires the X509_V_FLAG_USE_DELTAS flag to be enabled in\u003cbr\u003ethe verification context, the certificate being verified to contain a\u003cbr\u003efreshestCRL extension or the base CRL to have the EXFLAG_FRESHEST flag set, and\u003cbr\u003ean attacker to provide a malformed CRL to an application that processes it.\u003cbr\u003e\u003cbr\u003eThe vulnerability is limited to Denial of Service and cannot be escalated to\u003cbr\u003eachieve code execution or memory disclosure. For that reason the issue was\u003cbr\u003eassessed as Low severity according to our Security Policy.\u003cbr\u003e\u003cbr\u003eThe FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this issue,\u003cbr\u003eas the affected code is outside the OpenSSL FIPS module boundary.\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-476\", \"description\": \"CWE-476 NULL Pointer Dereference\"}]}], \"providerMetadata\": {\"orgId\": \"3a12439a-ef3a-4c79-92e6-6081a721f1e5\", \"shortName\": \"openssl\", \"dateUpdated\": \"2026-04-07T22:00:52.382Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-28388\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-04-10T20:18:43.095Z\", \"dateReserved\": \"2026-02-27T13:45:02.161Z\", \"assignerOrgId\": \"3a12439a-ef3a-4c79-92e6-6081a721f1e5\", \"datePublished\": \"2026-04-07T22:00:52.382Z\", \"assignerShortName\": \"openssl\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


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Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.