CVE intelligence

CVE-2026-99030

Vulnerability intelligence

Published Oct 23, 2026Sources checked Nov 10, 2026

7.5HIGHCVSS out of 10

What this means

Review the available evidence

CVE-2026-99030 and is rated High severity with a CVSS score of 7.5. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

CISA KEVNot listedBased on the latest collected catalog

EPSS0.5%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-99030?

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().

Source: NVD