Security readout for executives and security teams
Plain-English summary
CVE-2021-33456 is a crash bug in Yasm 1.3.0, an assembler. A specially crafted input can trigger a NULL pointer dereference while Yasm handles NASM-style preprocessing. The likely business impact is denial of service in developer, build, or analysis workflows that process untrusted assembly input.
Executive priority
Low immediate urgency for most organizations, unless Yasm is used in automated services that process untrusted code. Prioritize inventory and vendor tracking over emergency response because severity, exploitation, and fix details are incomplete.
Technical view
The reported flaw is a NULL pointer dereference in hash() within modules/preprocs/nasm/nasm-pp.c in Yasm 1.3.0. The provided sources do not include CVSS, CWE, patch status, or broader affected-version detail. Treat impact as input-triggered process crash unless vendor guidance states otherwise.
Likely exposure
Exposure is most likely where Yasm 1.3.0 is installed in CI, packaging, malware analysis, fuzzing, or developer build systems that process third-party source files. Internet-facing exposure is not indicated by the provided sources.
Exploitation context
The CVE is not listed as KEV, and the source bundle does not cite active exploitation. Public references appear to include an upstream issue and a gist, but no source in the bundle establishes real-world exploitation.
Researcher notes
Key missing evidence includes CVSS scoring, exact trigger conditions, fixed version, distribution advisories, and whether versions beyond 1.3.0 are affected. Do not assume code execution; the described condition supports a crash-class denial-of-service assessment only.
Mitigation direction
- Inventory systems and build containers for Yasm 1.3.0 usage.
- Check upstream or distribution vendor guidance for fixed packages or recommended workarounds.
- Avoid processing untrusted assembly inputs with affected Yasm until guidance is confirmed.
- Run affected build jobs in isolated, restartable workers with resource limits.
Validation and detection
- Confirm installed Yasm versions across CI images, developer systems, and build hosts.
- Identify workflows where Yasm processes third-party or externally supplied source files.
- Review build logs for recurring Yasm crashes during NASM preprocessing.
- Track the upstream issue and CVE record for patch or affected-version clarification.
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
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CVE-2021-33456 mapping review
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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/yasm/yasm/issues/175CVE reference · x_refsource_MISC
- https://gist.github.com/Clingto/bb632c0c463f4b2c97e4f65f751c5e6dCVE reference · x_refsource_MISC
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.