Local privilege escalation via inactive chain lookup
Published Jul 5, 2023 · Updated Mar 5, 2025
Use-after-free in Linux Kernel nftables allows local users to gain kernel privileges through a crafted chain-ID lookup. The nft_chain_lookup_byid function ignores the generation mask and can return a deleted chain, leaving a dangling reference during rule insertion. The attack requires CAP_NET_ADMIN in any user or network namespace; successful exploitation grants kernel-level privilege, while a failed attempt can crash the host.
Summary
What happened
Use-after-free in Linux Kernel nftables allows local users to gain kernel privileges through a crafted chain-ID lookup. The nft_chain_lookup_byid function ignores the generation mask and can return a deleted chain, leaving a dangling reference during rule insertion. The attack requires CAP_NET_ADMIN in any user or network namespace; successful exploitation grants kernel-level privilege, while a failed attempt can crash the host.
The record
- CVE
- CVE-2023-31248
- Published
- Jul 5, 2023
- Updated
- Mar 5, 2025
- Vendor
- The Linux Kernel Organization
- Product
- Linux Kernel
- Classifications
- CWE-416, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Jul 5, 2023CVE publishedPublication date reported by the CVE source.
- Mar 5, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=v5.9-rc1
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- STAR Labs CVE-2023-31248 proof-of-conceptproof of concept · unverified
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo