Heap Buffer Over-read in OpenSSL ASN.1 Content Parsing
CVE-2026-34180 is a low-severity vulnerability in OpenSSL's ASN.1 decoder caused by integer truncation when parsing crafted DER-encoded ASN.1 primitive elements whose content length exceeds 2 gigabytes. On affected 64-bit Unix and Unix-like platforms, the oversized length is mishandled during decoding of attacker-controlled ASN.1 data passed to functions such as d2i_X509(), d2i_PKCS7(), and other d2i_* decoders. In the worst case, the truncated length is treated as a request to scan binary content for a terminating zero byte, which can cause a heap buffer over-read and result in the decoded ASN.1 object incorporating memory beyond the end of the input buffer. OpenSSL command-line tools are not affected because BIO-layer checks prevent the vulnerable code path. The issue does not affect 32-bit platforms or 64-bit Windows.
Are you exposed to this one?
Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.
Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
If you can’t patch tonight, do this now.
Remediation
Patch, then assume compromise.
Exploits
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Affected products & vendors
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
23 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
An OpenSSL vulnerability addressed in Alpine Linux 3.22.5 and 3.23.5 as part of the June 9, 2026 OpenSSL advisory.
An OpenSSL vulnerability addressed in Alpine Linux 3.24.1 as part of the June 9, 2026 advisory.
A low-severity OpenSSL heap buffer over-read in ASN.1 content parsing caused by integer truncation in the ASN.1 decoder when parsing oversized DER-encoded primitive elements, potentially causing denial of service or unintended memory reads.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.