- Published
- Source
- CSO Online UK
- Filed under
- UK industry, Malware & exploits
- Vulnerabilities
- 1 CVE
The Linux kernel’s networking stack was found vulnerable to a guest-to-host escape attack, in which an attacker operating inside a virtual machine (VM) could cross the isolation boundary and access the underlying host. Dubbed PwnEscape and tracked as CVE-2026-99999, a flaw allowed guest-controlled packet metadata to trigger a write that changes an IPv4 header after the kernel has already processed it. That flaw could be chained with additional exploitation techniques to achieve host-level code execution. The problem was discovered by…
If you run the affected product
- Find every instance – especially the ones reachable from the internet.
- Apply the vendor's patch or mitigation now: exploited flaws are fixed in days, not at the next patch cycle.
- Then check for signs it was used before you patched: web shells, new accounts, unusual outbound traffic.
More helpCISA's Known Exploited Vulnerabilities catalogue (opens in a new tab)
The vulnerabilities in this story
CVE-2026-99999 in the NVD (opens in a new tab)
- CVSS9.3Critical
- CISA KEVNot listedno confirmed exploitation on CISA’s list (yet)
Exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog (CC0). Exploit prediction: EPSS by FIRST. This product uses the NVD API but is not endorsed or certified by the NVD.
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