Heap Buffer Over-read in ASN.1 Content Parsing

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Summary

CVECVE-2026-34180
StatePUBLISHED
Assigneropenssl
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-09 17:17:04 UTC
Updated2026-06-10 08:16:22 UTC
DescriptionIssue summary: Parsing a crafted DER-encoded ASN.1 structure with a primitive element whose content exceeds 2 gigabytes in length may cause a heap buffer over-read on 64-bit Unix and Unix-like platforms. Impact summary: The heap buffer over-read may crash the application (Denial of Service) or to load into the decoded ASN.1 object contents of memory beyond the end of the input buffer. More typically such ASN.1 elements would instead be truncated. An integer truncation in OpenSSL's ASN.1 decoder causes the content length of an ASN.1 primitive element to be mishandled when it exceeds 2 gigabytes. In the worst case the truncated length is treated as a request to scan the binary content for a terminating zero byte, possibly causing OpenSSL to read either less than or beyond the end of the allocated buffer. Applications that pass attacker-supplied data to d2i_X509(), d2i_PKCS7(), or any other d2i_* decoding function are affected. OpenSSL's own command-line tools are not vulnerable, as data read through the BIO layer is checked before it reaches the affected code. The issue only affects 64-bit Unix and Unix-like platforms; 32-bit platforms and 64-bit Windows are not affected. The FIPS modules in 4.0, 3.6, 3.5, 3.4 and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from ADP

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

Problem Types: CWE-125 | CWE-125 CWE-125 Out-of-bounds Read

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA OpenSSL OpenSSL affected 4.0.0 4.0.1 semver Not specified
CNA OpenSSL OpenSSL affected 3.6.0 3.6.3 semver Not specified
CNA OpenSSL OpenSSL affected 3.5.0 3.5.7 semver Not specified
CNA OpenSSL OpenSSL affected 3.4.0 3.4.6 semver Not specified
CNA OpenSSL OpenSSL affected 3.0.0 3.0.21 semver Not specified
CNA OpenSSL OpenSSL affected 1.1.1 1.1.1zh custom Not specified
CNA OpenSSL OpenSSL affected 1.0.2 1.0.2zq custom Not specified

References

ReferenceSourceLinkTags
github.com/openssl/openssl/commit/f696c73c3e61b8c502d040af62e690c060908a16 [email protected] github.com
github.com/openssl/openssl/commit/da5d62af75f69d6fbf7803743d7c56ac75461e43 [email protected] github.com
github.com/openssl/openssl/commit/cbe418ae978539cf14a398a207dba834c0e93e83 [email protected] github.com
github.com/openssl/openssl/commit/1c6908e4fa5fa568752221d8eaf561a809751e5d [email protected] github.com
github.com/openssl/openssl/commit/d93853c42110d6319e3df07842b488cb9f7ac5ff [email protected] github.com
openssl-library.org/news/secadv/20260609.txt [email protected] openssl-library.org
github.com/openssl/security/commit/1c6908e4fa5fa568752221d8eaf561a809751e5d MITRE github.com
github.com/openssl/security/commit/cbe418ae978539cf14a398a207dba834c0e93e83 MITRE github.com
github.com/openssl/security/commit/d93853c42110d6319e3df07842b488cb9f7ac5ff MITRE github.com
github.com/openssl/security/commit/da5d62af75f69d6fbf7803743d7c56ac75461e43 MITRE github.com
github.com/openssl/security/commit/f696c73c3e61b8c502d040af62e690c060908a16 MITRE github.com
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: Frank Buss (en)

CNA: Viktor Dukhovni (en)

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