netfilter: nf_conncount: fix zone comparison in tuple dedup

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-72247
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-15 06:21:51 UTC
Updated2026-08-17 06:18:26 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conncount: fix zone comparison in tuple dedup The "already exists" dedup logic in __nf_conncount_add() decides whether a connection has already been counted and can be skipped instead of incrementing the connlimit count. It compares the conntrack zone of a list entry with the zone of the connection being added using nf_ct_zone_id() and nf_ct_zone_equal(), passing conn->zone.dir or zone->dir as the direction argument. Those helpers take enum ip_conntrack_dir values: IP_CT_DIR_ORIGINAL is 0 and IP_CT_DIR_REPLY is 1. However, zone->dir is a u8 bitmask: NF_CT_ZONE_DIR_ORIG is 1, NF_CT_ZONE_DIR_REPL is 2 and NF_CT_DEFAULT_ZONE_DIR is 3. Passing that bitmask as the enum direction shifts the meaning of every non-zero value. An ORIG-only zone passes 1 and is tested as REPLY, while REPL-only and default zones pass 2 or 3 and test bits beyond the valid direction range. In those cases nf_ct_zone_id() can fall back to NF_CT_DEFAULT_ZONE_ID instead of using the real zone id, so different zones can be treated as equal and dedup collapses to tuple equality alone. nf_conncount stores and compares the original-direction tuple for a connection. If an skb already has an attached conntrack entry, get_ct_or_tuple_from_skb() explicitly copies ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, regardless of the packet's ctinfo. Therefore the zone comparison in the tuple dedup path must use IP_CT_DIR_ORIGINAL as well; the zone direction bitmask describes where a zone id applies, not which direction this conncount tuple represents. Fix the two dedup comparisons by passing IP_CT_DIR_ORIGINAL directly. Do not special-case NF_CT_DEFAULT_ZONE_DIR and do not compare raw zone ids: using the existing helpers with IP_CT_DIR_ORIGINAL preserves the direction-aware NF_CT_DEFAULT_ZONE_ID fallback. A default bidirectional zone contains the ORIG bit, so it naturally returns the real zone id; reply-only zones continue to fall back for original-direction tuple comparisons.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

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

EPSS: 0.002100000 probability, percentile 0.115920000 (date 2026-08-16)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 21ba8847f857028dc83a0f341e16ecc616e34740 82fc35e0da9a91db9a034f8311f18f77a599ae3f git Not specified
CNA Linux Linux affected 21ba8847f857028dc83a0f341e16ecc616e34740 78b5d6dbc860776161f9e9206b06ff8a01f531ab git Not specified
CNA Linux Linux affected 21ba8847f857028dc83a0f341e16ecc616e34740 4f30a89c0ed2418719a1144881c2635b940b543d git Not specified
CNA Linux Linux affected 21ba8847f857028dc83a0f341e16ecc616e34740 7bdc3c0985ecf17b957811fedcc684acdf698acc git Not specified
CNA Linux Linux affected 21ba8847f857028dc83a0f341e16ecc616e34740 35a56e2a46b90e6bd4ca816b80e9cb8d20dfc3ce git Not specified
CNA Linux Linux affected 21ba8847f857028dc83a0f341e16ecc616e34740 3cd9a5792cbea81139c24320986dd0db69e9b5d0 git Not specified
CNA Linux Linux affected 21ba8847f857028dc83a0f341e16ecc616e34740 6ff07ac5405bea4d4ead3559fc123f987576424a git Not specified
CNA Linux Linux affected 21ba8847f857028dc83a0f341e16ecc616e34740 f62c41b4910e65da396ec9a8c40c1fe7fe82e449 git Not specified
CNA Linux Linux affected 525e1dffed8711973f77412729621098a95238e5 git Not specified
CNA Linux Linux affected 75af3d78168e654a5cd8bbc4c774f97be836165f git Not specified
CNA Linux Linux affected 4.14.92 4.15 semver Not specified
CNA Linux Linux affected 4.18 Not specified
CNA Linux Linux unaffected 4.18 semver Not specified
CNA Linux Linux unaffected 5.10.261 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.212 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.178 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.145 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.97 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.40 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.5 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/6ff07ac5405bea4d4ead3559fc123f987576424a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/82fc35e0da9a91db9a034f8311f18f77a599ae3f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/78b5d6dbc860776161f9e9206b06ff8a01f531ab 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/3cd9a5792cbea81139c24320986dd0db69e9b5d0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/7bdc3c0985ecf17b957811fedcc684acdf698acc 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f62c41b4910e65da396ec9a8c40c1fe7fe82e449 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/35a56e2a46b90e6bd4ca816b80e9cb8d20dfc3ce 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/4f30a89c0ed2418719a1144881c2635b940b543d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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