CVE-2023-54243: In the Linux kernel, the following vulnerability has been resolved: netfilter: ebtables: fix table blob use-after-free We are not allowed to return ...

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: ebtables: fix table blob use-after-free We are not allowed to return an error at this point. Looking at the code it looks like ret is always 0 at this point, but its not. t = find_table_lock(net, repl->name, &ret, &ebt_mutex); ... this can return a valid table, with ret != 0. This bug causes update of table->private with the new blob, but then frees the blob right away in the caller. Syzbot report: BUG: KASAN: vmalloc-out-of-bounds in __ebt_unregister_table+0xc00/0xcd0 net/bridge/netfilter/ebtables.c:1168 Read of size 4 at addr ffffc90005425000 by task kworker/u4:4/74 Workqueue: netns cleanup_net Call Trace: kasan_report+0xbf/0x1f0 mm/kasan/report.c:517 __ebt_unregister_table+0xc00/0xcd0 net/bridge/netfilter/ebtables.c:1168 ebt_unregister_table+0x35/0x40 net/bridge/netfilter/ebtables.c:1372 ops_exit_list+0xb0/0x170 net/core/net_namespace.c:169 cleanup_net+0x4ee/0xb10 net/core/net_namespace.c:613 ... ip(6)tables appears to be ok (ret should be 0 at this point) but make this more obvious.

Metrics

CVSS 3.1

7.8/10

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

EPSS Probability

0.17%

7.1th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= c58dd2dd443c26d856a168db108a0cd11c285bf3, < 9060abce3305ab2354c892c09d5689df51486df5; >= c58dd2dd443c26d856a168db108a0cd11c285bf3, < dbb3cbbf03b3c52cb390fabec357f1e4638004f5; >= c58dd2dd443c26d856a168db108a0cd11c285bf3, < 3dd6ac973351308d4117eda32298a9f1d68764fd; >= c58dd2dd443c26d856a168db108a0cd11c285bf3, < cda0e0243bd3c04008fcd37a46b0269fb3c49249; >= c58dd2dd443c26d856a168db108a0cd11c285bf3, < e58a171d35e32e6e8c37cfe0e8a94406732a331f; a3bc0f8ea439762aa62d40a295157410498cbea7; 8ed40c122919cd79bc3c059e5864e5e7d9d455f0; c5e4ef499cfc78de45a4f01b8c557b5964d77c53; f34728610b2a8c7b9864f9404f2884c17f6fca5c; 8b5740915a9faa8b1fa9166193a33e2a9ae30ec6; >= 3.2.60, < 3.3; >= 3.4.91, < 3.5; >= 3.10.41, < 3.11; >= 3.12.21, < 3.13; >= 3.14.5, < 3.15
Linux	Linux	3.15

References

Timeline

Published: Dec 30, 2025
Last Modified: Aug 4, 2026
Status: Deferred

Frequently Asked Questions

What is CVE-2023-54243?

In the Linux kernel, the following vulnerability has been resolved: netfilter: ebtables: fix table blob use-after-free We are not allowed to return an error at this point. Looking at the code it looks like ret is always 0 at this point, but its not. t = find_table_lock(net, repl->name, &ret, &ebt_mutex); ... this can return a valid table, with ret != 0. This bug causes update of table->private with the new blob, but then frees the blob right away in the caller. Syzbot report: BUG: KASAN: vmalloc-out-of-bounds in __ebt_unregister_table+0xc00/0xcd0 net/bridge/netfilter/ebtables.c:1168 Read of size 4 at addr ffffc90005425000 by task kworker/u4:4/74 Workqueue: netns cleanup_net Call Trace: kasan_report+0xbf/0x1f0 mm/kasan/report.c:517 __ebt_unregister_table+0xc00/0xcd0 net/bridge/netfilter/ebtables.c:1168 ebt_unregister_table+0x35/0x40 net/bridge/netfilter/ebtables.c:1372 ops_exit_list+0xb0/0x170 net/core/net_namespace.c:169 cleanup_net+0x4ee/0xb10 net/core/net_namespace.c:613 ... ip(6)tables appears to be ok (ret should be 0 at this point) but make this more obvious.

How severe is CVE-2023-54243?

CVE-2023-54243 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.17% probability of exploitation in the next 30 days.

How do I fix CVE-2023-54243?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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