CVE-2026-63076 (GCVE-0-2026-63076)

Vulnerability from cvelistv5 – Published: 2026-08-25 13:00 – Updated: 2026-08-25 14:37
VLAI
Title
Invalid Pointer Dereference in CMP Server via Crafted protectionAlg
Summary
Issue summary: OpenSSL CMP password based protection verification only checks whether the protectionAlg parameter was not NULL and not its ASN.1 type, before treating it as a PBMParameter. A crafted message can contain a parameter of a different type, which is then dereferenced as an invalid pointer. Impact summary: A remote, unauthenticated attacker can crash an application acting as a CMP server that accepts PBM-protected messages, or a CMP client talking to a malicious or intercepted CMP server, resulting in a Denial of Service. CWE: CWE-476: NULL Pointer Dereference Description: When verifying the password-based MAC protection of a CMP message, OpenSSL library reads the protectionAlg algorithm parameter with X509_ALGOR_get0(), which returns both the parameter type and its value pointer. The value is then cast to an ASN1_STRING and treated as the expected PBMParameter after only checking that pointer is not NULL. The parameter type returned by X509_ALGOR_get0() was never consulted. This happens during protection verification, before any MAC is computed, so no knowledge of the PBM shared secret is required; the only precondition is that PBM verification is reachable. On the server side this is reached from OSSL_CMP_SRV_process_request() for any application that stands up a CMP server accepting PBM-protected messages, and on the client side from CMP response validation against a malicious or on-path (MITM) server. The reliable consequence is a denial of service; there is no memory disclosure, no controlled memory write, and no path to code execution. CMP is a specialized feature that an application must explicitly enable. FIPS impact: no As the CMP code lives outside the FIPS module boundary, no FIPS modules are affected by this CVE.
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 · CISA-ADP (v2.0.3)
Decision recorded 2026-08-25 14:37 UTC
CWE
  • CWE-476 - NULL Pointer Dereference
Assigner
References
Impacted products
Vendor Product Version CPE status
OpenSSL OpenSSL Affected: 4.0.0 , < 4.0.2 (semver)
Affected: 3.6.0 , < 3.6.4 (semver)
Affected: 3.5.0 , < 3.5.8 (semver)
Affected: 3.4.0 , < 3.4.7 (semver)
Affected: 3.0.0 , < 3.0.22 (semver)
guessed Create a notification for this product.
Date Public
2026-08-25 11:36
Credits
Ying Dong Bhabani Sankar Das Daniel Kubec
Show details on NVD website
To clipboard 

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A crafted message can\u003cbr\u003econtain a parameter of a different type, which is then dereferenced as an\u003cbr\u003einvalid pointer.\u003cbr\u003e\u003cbr\u003eImpact summary: A remote, unauthenticated attacker can crash an application\u003cbr\u003eacting as a CMP server that accepts PBM-protected messages, or a CMP client\u003cbr\u003etalking to a malicious or intercepted CMP server, resulting in a Denial of\u003cbr\u003eService.\u003cbr\u003e\u003cbr\u003eCWE: CWE-476: NULL Pointer Dereference\u003cbr\u003e\u003cbr\u003eDescription: When verifying the password-based MAC protection of a CMP\u003cbr\u003emessage, OpenSSL library reads the protectionAlg algorithm parameter with\u003cbr\u003eX509_ALGOR_get0(), which returns both the parameter type and its value\u003cbr\u003epointer. The value is then cast to an ASN1_STRING and treated as the\u003cbr\u003eexpected PBMParameter after only checking that pointer is not NULL. The\u003cbr\u003eparameter type returned by X509_ALGOR_get0() was never consulted.\u003cbr\u003e\u003cbr\u003eThis happens during protection verification, before any MAC is computed, so\u003cbr\u003eno knowledge of the PBM shared secret is required; the only precondition is\u003cbr\u003ethat PBM verification is reachable. On the server side this is reached from\u003cbr\u003eOSSL_CMP_SRV_process_request() for any application that stands up a CMP\u003cbr\u003eserver accepting PBM-protected messages, and on the client side from CMP\u003cbr\u003eresponse validation against a malicious or on-path (MITM) server. The\u003cbr\u003ereliable consequence is a denial of service; there is no memory disclosure,\u003cbr\u003eno controlled memory write, and no path to code execution. CMP is a\u003cbr\u003especialized feature that an application must explicitly enable.\u003cbr\u003e\u003cbr\u003eFIPS impact: no\u003cbr\u003eAs the CMP code lives outside the FIPS module boundary, no FIPS modules\u003cbr\u003eare affected by this CVE.\", \"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\": \"2026-08-25T13:00:11.218Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-63076\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-08-25T14:37:32.193Z\", \"dateReserved\": \"2026-07-15T13:10:26.188Z\", \"assignerOrgId\": \"3a12439a-ef3a-4c79-92e6-6081a721f1e5\", \"datePublished\": \"2026-08-25T13:00:11.218Z\", \"assignerShortName\": \"openssl\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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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.