Firewall policy bypass via stale PIPAPO bitmap bits
Published Jan 23, 2025 · Updated Aug 5, 2026
Improper packet filtering in the Linux kernel allows remote attackers to bypass nftables rules via crafted packet headers. The nft_pipapo_lookup operation seeds its initial result bitmap through the total map width instead of the first field's width, leaving one-bits that survive later result/fill swaps and create false set matches. Exposure requires an nftables PIPAPO concatenated-range set whose first field is smaller than a later field; false matches can admit denied traffic, redirect mapped traffic, or blackhole permitted flows.
Summary
What happened
Improper packet filtering in the Linux kernel allows remote attackers to bypass nftables rules via crafted packet headers. The nft_pipapo_lookup operation seeds its initial result bitmap through the total map width instead of the first field's width, leaving one-bits that survive later result/fill swaps and create false set matches. Exposure requires an nftables PIPAPO concatenated-range set whose first field is smaller than a later field; false matches can admit denied traffic, redirect mapped traffic, or blackhole permitted flows.
The record
- CVE
- CVE-2024-57947
- Published
- Jan 23, 2025
- Updated
- Aug 5, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- CWE-401, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jan 23, 2025CVE publishedPublication date reported by the CVE source.
- Aug 5, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=3c4287f62044a90e73a561aa05fc46e62da173da <69b6a67f7052905e928d75a0c5871de50e686986
- Affected versionversion=3c4287f62044a90e73a561aa05fc46e62da173da <77bf0c4ab928ca4c9a99311f4f70ba0c17fecba9
- Affected versionversion=3c4287f62044a90e73a561aa05fc46e62da173da <791a615b7ad2258c560f91852be54b0480837c93
- Affected versionversion=3c4287f62044a90e73a561aa05fc46e62da173da <8058c88ac0df21239daee54b5934d5c80ca9685f
- Affected versionversion=3c4287f62044a90e73a561aa05fc46e62da173da <957a4d1c4c5849e4515c9fb4db21bf85318103dc
- Affected versionversion=3c4287f62044a90e73a561aa05fc46e62da173da <9625c46ce6fd4f922595a4b32b1de5066d70464f
- Affected versionversion=5.6
What conditions does exploitation require?
What is affected?
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.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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