Security readout for executives and security teams
Plain-English summary
CVE-2021-33457 is a crash bug in Yasm 1.3.0, an assembler tool. A specially crafted input may cause Yasm to dereference a NULL pointer and terminate. The sources do not show code execution, privilege escalation, a CVSS score, or active exploitation.
Executive priority
Treat this as a targeted operational reliability risk, not an emergency, unless Yasm processes untrusted input in critical automated workflows. Prioritize inventory and vendor update checks.
Technical view
The flaw is a NULL pointer dereference in expand_mmac_params() within modules/preprocs/nasm/nasm-pp.c in Yasm 1.3.0. Based on the supplied description, expected impact is denial of service against Yasm processing, not confirmed system compromise.
Likely exposure
Exposure is likely limited to systems, build pipelines, developer workstations, or analysis tools that use Yasm 1.3.0 to process assembly source, especially untrusted or third-party input.
Exploitation context
The source bundle includes issue and gist references, but KEV is false and no supplied source states active exploitation. The public evidence supports a crash condition, not weaponized exploitation or remote compromise.
Researcher notes
Evidence is sparse: no CVSS, CWE, affected CPEs, patch version, or exploitation confirmation are included. Analysis should stay constrained to Yasm 1.3.0 and the named NULL dereference location.
Mitigation direction
- Inventory systems and containers for Yasm 1.3.0.
- Check upstream and distribution vendor guidance for fixed packages.
- Avoid processing untrusted assembly input with vulnerable Yasm versions.
- Run Yasm-based build jobs in isolated, resource-limited environments.
- Track the GitHub issue for confirmed fixes or maintainer updates.
Validation and detection
- Confirm whether Yasm 1.3.0 is installed or bundled.
- Map where Yasm processes third-party or user-controlled input.
- Review build logs for unexpected Yasm crashes.
- Check package manager metadata for patched downstream builds.
- Document any exposed pipeline that depends on vulnerable Yasm.
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-2021-33457 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/171CVE 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.