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7.5
CVE-2026-34180EXPLOITEDPATCHED
openssl · openssl

Heap Buffer Over-read in ASN.1 Content Parsing

Description

Issue 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.

Affected Products

VendorProductVersions
opensslopenssl4.0.0, 3.6.0, 3.5.0, 3.4.0, 3.0.0, 1.1.1, 1.0.2

Also Affects

Downstream vendors/products affected by this vulnerability

VendorProductSourceConfidence
ibmapp connect enterprisecert_advisory90%
oraclesolariscert_advisory90%
splunksplunk enterprisecert_advisory90%

References

  • https://openssl-library.org/news/secadv/20260609.txt(vendor-advisory)
  • https://github.com/openssl/openssl/commit/f696c73c3e61b8c502d040af62e690c060908a16(patch)
  • https://github.com/openssl/openssl/commit/d93853c42110d6319e3df07842b488cb9f7ac5ff(patch)
  • https://github.com/openssl/openssl/commit/da5d62af75f69d6fbf7803743d7c56ac75461e43(patch)
  • https://github.com/openssl/openssl/commit/1c6908e4fa5fa568752221d8eaf561a809751e5d(patch)
  • https://github.com/openssl/openssl/commit/cbe418ae978539cf14a398a207dba834c0e93e83(patch)

Related News (10 articles)

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Tier A
Microsoft MSRC72d ago
CVE-2026-34180 Heap Buffer Over-read in ASN.1 Content Parsing
→ No new info (linked only)
Tier B
CERT-FR75d ago
Multiples vulnérabilités dans OpenSSL (10 juin 2026)
→ No new info (linked only)
Tier C
VulDB75d ago
CVE-2026-34180 | OpenSSL up to 4.0.0 on Unix d2i_X509 out-of-bounds
→ No new info (linked only)
CVSS 3.17.5 HIGH
VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CISA KEV❌ No
Actively exploited✅ Yes
Patch available
null
CWECWE-125
PublishedJun 9, 2026
Last enriched75d agov2
Tags
CVE-2026-34180
Trending Score38
Source articles10
Independent4
Info Completeness8/14
Missing: cvss, epss, kev, exploit, iocs, mitre_attack

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Verification

State: unverified
Confidence: 0%

Vulnerability Timeline

CVE Published
Jun 9, 2026
Discovered by ZDM
Jun 9, 2026
Updated: description, affectedVersions, severity, activelyExploited, patchAvailable, tags
Jun 9, 2026
Actively Exploited
Jun 10, 2026
Patch Available
Jun 10, 2026

Version History

v2
Last enriched 75d ago
v2Tier C75d ago

Updated description with new details, added affected versions 3.0.20, 3.4.5, 3.5.6, 3.6.2, changed severity to HIGH, and noted that no exploit is available.

descriptionaffectedVersionsseverityactivelyExploitedpatchAvailabletags
via VulDB
v175d ago

Initial creation