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9.3
CVE-2026-99999: Linux kernel IPv4 processing can corrupt network header
CVE-2026-99999 · published today
Summary
The Linux operating system's core networking code can mishandle packets that contain incorrect checksum information, potentially altering the packet's header and causing network communication errors. This can affect any system running the Linux kernel, such as Debian or other Linux distributions. Apply the latest kernel updates from your Linux vendor to fix the issue and ensure only properly checksummed packets are accepted.
What to do
- Update linux kernel to version 7.2.11.
- Update linux linux to version a464d950f31c89565cbaae038cc60db04fe01956 or later.
Affected software
| Ecosystem | Vendor | Product | Affected versions |
|---|---|---|---|
| Debian:12 | debian | linux | All versions |
| – | linux | linux |
< a464d950f31c89565cbaae038cc60db04fe01956 2.6.27 |
| Linux | linux | kernel |
>= 6.19.0, < 7.2.11 Fix: upgrade to 7.2.11
|
Original advisory text
DEBIAN-CVE-2026-99999
In the Linux kernel, the following vulnerability has been resolved:
ipv4: validate checksum_start before completing checksum
If a packet with bad checksum metadata gets into the ipv4 stack,
skb_checksum_help can corrupt the network header and cause a bunch of
mischief.
This was discovered and reported by Paulos, and has been reporoduced
by others independently since.
We really shouldn't allow such packets in, but as a defence
in depth measure, let's also check before we complete the checksum.
A more complete validation at input is forthcoming, but needs more work.
ipv4: validate checksum_start before completing checksum
If a packet with bad checksum metadata gets into the ipv4 stack,
skb_checksum_help can corrupt the network header and cause a bunch of
mischief.
This was discovered and reported by Paulos, and has been reporoduced
by others independently since.
We really shouldn't allow such packets in, but as a defence
in depth measure, let's also check before we complete the checksum.
A more complete validation at input is forthcoming, but needs more work.
References
- https://git.kernel.org/stable/c/32a8b0adaa18e52aaa0b246b5ffe683075354dbb URL
- http://www.openwall.com/lists/oss-security/2026/10/15/5
- https://git.kernel.org/stable/c/0fab003ef4698e0628060a45a48f14b43ba2a40a URL
- https://git.kernel.org/stable/c/94524b7b32691de2e2ce162c04d6cbc9106e5cbf URL
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git Product
- https://git.kernel.org/stable/c/6785011f8b16abf40b1e9d8b2e332232b3e68822 URL
- https://git.kernel.org/stable/c/a464d950f31c89565cbaae038cc60db04fe01956 URL
- https://git.kernel.org/stable/c/a65f69e0f38ffbed1b128029e09097436416dc8b URL
- https://git.kernel.org/stable/c/c3e33464746166264334641dc850a36eef7e6326 URL
- https://git.kernel.org/stable/c/f3e835af6226f1dd12160cbd696081e9b6155de0 URL
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/99xxx/CVE-2026-99999... Vendor Advisory
- https://nvd.nist.gov/vuln/detail/CVE-2026-99999 Vendor Advisory
- https://vercel.com/blog/findings-from-the-1-million-dollar-vercel-sandbox-challe... Third Party Advisory
- https://security-tracker.debian.org/tracker/CVE-2026-99999 Vendor Advisory
- https://pwn.ai/blog/Pwnescape Third Party Advisory
Internet-facing
14 days
Internal
At next upgrade
- Not known to be exploited
- Needs hands-on effort to exploit (estimated)
- Gives an attacker full control (estimated)
Timeline
Published15 Oct 2026
Updated16 Oct 2026
First seen15 Oct 2026
Sources
CVE-2026-99999 · NVD
DEBIAN-CVE-2026-99999 · OSV
CVE-2026-99999 · MITRE
CVE-2026-99999 · OSV
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