ASN1_TYPE Type Confusion in the PKCS7_digest_from_attributes() function

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Summary

CVECVE-2026-22796
StatePUBLISHED
Assigneropenssl
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-01-27 16:16:35 UTC
Updated2026-05-12 13:17:32 UTC
DescriptionIssue summary: A type confusion vulnerability exists in the signature verification of signed PKCS#7 data where an ASN1_TYPE union member is accessed without first validating the type, causing an invalid or NULL pointer dereference when processing malformed PKCS#7 data. Impact summary: An application performing signature verification of PKCS#7 data or calling directly the PKCS7_digest_from_attributes() function can be caused to dereference an invalid or NULL pointer when reading, resulting in a Denial of Service. The function PKCS7_digest_from_attributes() accesses the message digest attribute value without validating its type. When the type is not V_ASN1_OCTET_STRING, this results in accessing invalid memory through the ASN1_TYPE union, causing a crash. Exploiting this vulnerability requires an attacker to provide a malformed signed PKCS#7 to an application that verifies it. The impact of the exploit is just a Denial of Service, the PKCS7 API is legacy and applications should be using the CMS API instead. For these reasons the issue was assessed as Low severity. The FIPS modules in 3.5, 3.4, 3.3 and 3.0 are not affected by this issue, as the PKCS#7 parsing implementation is outside the OpenSSL FIPS module boundary. OpenSSL 3.6, 3.5, 3.4, 3.3, 3.0, 1.1.1 and 1.0.2 are vulnerable to this issue.

Risk And Classification

Primary CVSS: v3.1 5.3 MEDIUM from ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Problem Types: CWE-754 | CWE-754 CWE-754 Improper Check for Unusual or Exceptional Conditions

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Openssl Openssl All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA OpenSSL OpenSSL affected 3.6.0 3.6.1 semver Not specified
CNA OpenSSL OpenSSL affected 3.5.0 3.5.5 semver Not specified
CNA OpenSSL OpenSSL affected 3.4.0 3.4.4 semver Not specified
CNA OpenSSL OpenSSL affected 3.3.0 3.3.6 semver Not specified
CNA OpenSSL OpenSSL affected 3.0.0 3.0.19 semver Not specified
CNA OpenSSL OpenSSL affected 1.1.1 1.1.1ze custom Not specified
CNA OpenSSL OpenSSL affected 1.0.2 1.0.2zn custom Not specified
ADP Siemens SIMATIC S7-1500 TM MFP - GNU/Linux Subsystem affected * custom Not specified

References

ReferenceSourceLinkTags
github.com/openssl/openssl/commit/eeee3cbd4d682095ed431052f00403004596373e [email protected] github.com Patch
github.com/openssl/openssl/commit/7bbca05be55b129651d9df4bdb92becc45002c12 [email protected] github.com Patch
cert-portal.siemens.com/productcert/html/ssa-265688.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
github.com/openssl/openssl/commit/2502e7b7d4c0cf4f972a881641fe09edc67aeec4 [email protected] github.com Patch
openssl-library.org/news/secadv/20260127.txt [email protected] openssl-library.org Vendor Advisory
github.com/openssl/openssl/commit/572844beca95068394c916626a6d3a490f831a49 [email protected] github.com Patch
github.com/openssl/openssl/commit/ef2fb66ec571564d64d1c74a12e388a2a54d05d2 [email protected] github.com Patch
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Luigino Camastra (Aisle Research) (en)

CNA: Bob Beck (en)

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