Security readout for executives and security teams
Plain-English summary
This flaw can make YARA 3.5.0 crash or exhaust stack resources when it processes a specially crafted rule. The business impact is service disruption in systems that compile or accept YARA rules from outside trusted control, such as scanning pipelines or security automation.
Executive priority
Treat as targeted operational risk, not confirmed widespread emergency. Prioritize scanners, sandboxes, CI jobs, and security services that ingest external YARA rules because disruption there can reduce detection coverage.
Technical view
The issue is in libyara/re.c in YARA 3.5.0. The regexp module mishandles crafted rules involving hex strings in _yr_re_emit, causing stack consumption and denial of service. The CVE states it is distinct from CVE-2017-9304.
Likely exposure
Exposure is most likely where YARA 3.5.0 or embedded libyara parses user-supplied, third-party, or automatically ingested rules. Systems using only vetted internal rules have lower exposure, but should still verify package status.
Exploitation context
The source bundle does not show KEV listing or cited active exploitation. The described attacker path requires getting a crafted YARA rule processed by a vulnerable YARA/libyara instance.
Researcher notes
Evidence is limited to the CVE description, upstream GitHub issue and commit, and Fedora advisories. The bundle provides no CVSS, CWE, detailed affected-product matrix, or active-exploitation evidence.
Mitigation direction
- Upgrade YARA/libyara to a version containing the upstream fix.
- Apply vendor or distribution security updates where YARA is packaged.
- Do not process untrusted YARA rules without review and controls.
- Add resource limits around rule compilation in exposed automation.
- Check current vendor guidance for supported fixed versions.
Validation and detection
- Inventory systems and products using YARA or embedded libyara.
- Confirm whether YARA 3.5.0 is present or backported by the vendor.
- Review rule-ingestion paths for third-party or user-controlled rules.
- Verify package updates against upstream commit or vendor advisories.
- Run trusted regression coverage for rule parsing after updating.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
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-2017-9438 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
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.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/VirusTotal/yara/issues/674CVE reference · x_refsource_CONFIRM
- https://github.com/VirusTotal/yara/commit/10e8bd3071677dd1fa76beeef4bc2fc427cea5e7CVE reference · x_refsource_CONFIRM
- FEDORA-2021-f41d5fc954CVE reference · vendor-advisory, x_refsource_FEDORA
- FEDORA-2021-dd62918333CVE reference · vendor-advisory, x_refsource_FEDORA
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.