GHSA-2HRC-J4GC-H2P8
Vulnerability from github – Published: 2025-12-30 15:30 – Updated: 2026-08-04 12:34In 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.
{
"affected": [],
"aliases": [
"CVE-2023-54243"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-12-30T13:16:12Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: ebtables: fix table blob use-after-free\n\nWe are not allowed to return an error at this point.\nLooking at the code it looks like ret is always 0 at this\npoint, but its not.\n\nt = find_table_lock(net, repl-\u003ename, \u0026ret, \u0026ebt_mutex);\n\n... this can return a valid table, with ret != 0.\n\nThis bug causes update of table-\u003eprivate with the new\nblob, but then frees the blob right away in the caller.\n\nSyzbot report:\n\nBUG: KASAN: vmalloc-out-of-bounds in __ebt_unregister_table+0xc00/0xcd0 net/bridge/netfilter/ebtables.c:1168\nRead of size 4 at addr ffffc90005425000 by task kworker/u4:4/74\nWorkqueue: netns cleanup_net\nCall Trace:\n kasan_report+0xbf/0x1f0 mm/kasan/report.c:517\n __ebt_unregister_table+0xc00/0xcd0 net/bridge/netfilter/ebtables.c:1168\n ebt_unregister_table+0x35/0x40 net/bridge/netfilter/ebtables.c:1372\n ops_exit_list+0xb0/0x170 net/core/net_namespace.c:169\n cleanup_net+0x4ee/0xb10 net/core/net_namespace.c:613\n...\n\nip(6)tables appears to be ok (ret should be 0 at this point) but make\nthis more obvious.",
"id": "GHSA-2hrc-j4gc-h2p8",
"modified": "2026-08-04T12:34:49Z",
"published": "2025-12-30T15:30:32Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-54243"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3dd6ac973351308d4117eda32298a9f1d68764fd"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9060abce3305ab2354c892c09d5689df51486df5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/cda0e0243bd3c04008fcd37a46b0269fb3c49249"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/dbb3cbbf03b3c52cb390fabec357f1e4638004f5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e58a171d35e32e6e8c37cfe0e8a94406732a331f"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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