CVE-2026-23111

Highest-risk unexploited with PoCs

Exploit code exists, no confirmed in-the-wild activity, ranked by EPSS

Actively Exploited

Confirmed exploited in the wild, sorted by most recently updated

CVSS 7.8EPSS <1%

Published 2026-02-13Updated 2026-06-09

Media 8810887PoC

Vulnerability details

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: fix inverted genmask check in nft_map_catchall_activate() nft_map_catchall_activate() has an inverted element activity check compared to its non-catchall counterpart nft_mapelem_activate() and compared to what is logically required. nft_map_catchall_activate() is called from the abort path to re-activate catchall map elements that were deactivated during a failed transaction. It should skip elements that are already active (they don't need re-activation) and process elements that are inactive (they need to be restored). Instead, the current code does the opposite: it skips inactive elements and processes active ones. Compare the non-catchall activate callback, which is correct: nft_mapelem_activate(): if (nft_set_elem_active(ext, iter->genmask)) return 0; /* skip active, process inactive */ With the buggy catchall version: nft_map_catchall_activate(): if (!nft_set_elem_active(ext, genmask)) continue; /* skip inactive, process active */ The consequence is that when a DELSET operation is aborted, nft_setelem_data_activate() is never called for the catchall element. For NFT_GOTO verdict elements, this means nft_data_hold() is never called to restore the chain->use reference count. Each abort cycle permanently decrements chain->use. Once chain->use reaches zero, DELCHAIN succeeds and frees the chain while catchall verdict elements still reference it, resulting in a use-after-free. This is exploitable for local privilege escalation from an unprivileged user via user namespaces + nftables on distributions that enable CONFIG_USER_NS and CONFIG_NF_TABLES. Fix by removing the negation so the check matches nft_mapelem_activate(): skip active elements, process inactive ones.

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

CNALinux

EPSS score history

Sources

6 links

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Profile

CVSS

7.8

EPSS

<1%

Published

2026-02-13

Updated

2026-06-09

CNA

Linux

Vendors

Linux

1 product

CPEs

cpe:/o:redhat:enterprise_linux_eus:10.0

cpe:/o:redhat:enterprise_linux:10.2

cpe:/a:redhat:rhel_eus:9.4::appstream

cpe:/a:redhat:rhel_eus:9.6::appstream

cpe:/a:redhat:enterprise_linux:9::appstream

cpe:/o:redhat:rhel_eus:9.4::baseos

cpe:/o:redhat:rhel_eus:9.6::baseos

cpe:/o:redhat:enterprise_linux:9::baseos

cpe:/a:redhat:rhel_eus:9.4::crb

cpe:/a:redhat:rhel_eus:9.6::crb

cpe:/a:redhat:enterprise_linux:9::crb

cpe:/a:redhat:rhel_eus:9.4::nfv

cpe:/a:redhat:rhel_eus:9.6::nfv

cpe:/a:redhat:enterprise_linux:9::nfv

cpe:/a:redhat:rhel_eus:9.4::realtime

cpe:/a:redhat:rhel_eus:9.6::realtime

cpe:/a:redhat:enterprise_linux:9::realtime

cpe:/o:redhat:enterprise_linux:9

cpe:/o:redhat:enterprise_linux:6

cpe:/o:redhat:enterprise_linux:7

cpe:/o:redhat:enterprise_linux:8

cpe:/a:redhat:enterprise_linux:9

cpe:/a:redhat:rhel_eus:9.4

cpe:/a:redhat:rhel_eus:9.6

Vulnerability dashboard

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