LiveActive security incident?Get immediate response
CVE Record

CVE-2018-0739: Constructed ASN.1 types with a recursive definition could exceed the stack

Constructed ASN.1 types with a recursive definition (such as can be found in PKCS7) could eventually exceed the stack given malicious input with excessive recursion. This could result in a Denial Of Service attack. There are no such structures used within SSL/TLS that come from untrusted sources so this is considered safe. Fixed in OpenSSL 1.1.0h (Affected 1.1.0-1.1.0g). Fixed in OpenSSL 1.0.2o (Affected 1.0.2b-1.0.2n).

UnknownCVSS not scoredNot KEV-listedUpdated
Discuss exposureBack to CVEs
Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2018-0739 is an OpenSSL denial-of-service issue. Maliciously deep ASN.1 data, such as PKCS7 content, can exhaust process stack space and crash affected software. The source states SSL/TLS does not use these untrusted recursive structures, so typical TLS handshakes are not the main concern.

Executive priority

Treat as a patching priority for affected systems that parse untrusted encoded content. Business risk is service disruption, not confirmed compromise. TLS-only exposure appears limited based on the CVE source, but OpenSSL’s broad use warrants inventory and verification.

Technical view

Affected OpenSSL versions mishandle constructed ASN.1 types with recursive definitions. Excessive recursion in malicious input can exceed the stack and cause denial of service. Fixed releases are OpenSSL 1.1.0h and 1.0.2o; affected ranges are 1.1.0-1.1.0g and 1.0.2b-1.0.2n.

Likely exposure

Exposure is most likely where applications use affected OpenSSL to parse untrusted ASN.1 or PKCS7-like data. The provided source says untrusted SSL/TLS structures are considered safe, reducing exposure for ordinary TLS-only services.

Exploitation context

The bundle does not show KEV listing or cited evidence of active exploitation. Public advisories confirm vendor updates, but the provided evidence supports denial of service only, not code execution or data theft.

Researcher notes

Severity data and CVSS are absent in the supplied bundle. The key technical constraint is the non-TLS ASN.1 parsing path. Avoid broad claims about all OpenSSL network services unless their data flow includes untrusted recursive ASN.1 structures.

Mitigation direction

  • Upgrade OpenSSL to 1.1.0h, 1.0.2o, or vendor-fixed packages.
  • Patch affected Linux distribution packages referenced by vendor advisories.
  • Prioritize applications parsing untrusted ASN.1, PKCS7, or similar encoded content.
  • Check vendor guidance for embedded or statically linked OpenSSL copies.
  • Restart dependent services after OpenSSL library updates where required.

Validation and detection

  • Inventory OpenSSL versions across hosts, containers, and appliances.
  • Confirm no systems run OpenSSL 1.1.0-1.1.0g or 1.0.2b-1.0.2n.
  • Identify services that parse untrusted ASN.1 or PKCS7 content.
  • Verify distribution security advisories are applied for relevant platforms.
  • Confirm statically linked applications were rebuilt against fixed OpenSSL.
Prepared
Confidence
high
Sources
8

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cve · low confidence lookup

CVE-2018-0739 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
29Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
OpenSSLOpenSSLFixed in OpenSSL 1.1.0h (Affected 1.1.0-1.1.0g), Fixed in OpenSSL 1.0.2o (Affected 1.0.2b-1.0.2n)Listed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.