CVE-2023-53317 [Medium] | Security Vulnerability in Linux Kernel

In the Linux kernel, the following vulnerability has been resolved: ext4: fix WARNING in mb_find_extent Syzbot found the following issue: EXT4-fs: Warning: mounting with data=journal disables delayed allocation, dioread_nolock, O_DIRECT and fast_commit support! EXT4-fs (loop0): orphan cleanup on readonly fs ------------[ cut here ]------------ WARNING: CPU: 1 PID: 5067 at fs/ext4/mballoc.c:1869 mb_find_extent+0x8a1/0xe30 Modules linked in: CPU: 1 PID: 5067 Comm: syz-executor307 Not tainted 6.2.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 RIP: 0010:mb_find_extent+0x8a1/0xe30 fs/ext4/mballoc.c:1869 RSP: 0018:ffffc90003c9e098 EFLAGS: 00010293 RAX: ffffffff82405731 RBX: 0000000000000041 RCX: ffff8880783457c0 RDX: 0000000000000000 RSI: 0000000000000041 RDI: 0000000000000040 RBP: 0000000000000040 R08: ffffffff82405723 R09: ffffed10053c9402 R10: ffffed10053c9402 R11: 1ffff110053c9401 R12: 0000000000000000 R13: ffffc90003c9e538 R14: dffffc0000000000 R15: ffffc90003c9e2cc FS: 0000555556665300(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000056312f6796f8 CR3: 0000000022437000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> ext4_mb_complex_scan_group+0x353/0x1100 fs/ext4/mballoc.c:2307 ext4_mb_regular_allocator+0x1533/0x3860 fs/ext4/mballoc.c:2735 ext4_mb_new_blocks+0xddf/0x3db0 fs/ext4/mballoc.c:5605 ext4_ext_map_blocks+0x1868/0x6880 fs/ext4/extents.c:4286 ext4_map_blocks+0xa49/0x1cc0 fs/ext4/inode.c:651 ext4_getblk+0x1b9/0x770 fs/ext4/inode.c:864 ext4_bread+0x2a/0x170 fs/ext4/inode.c:920 ext4_quota_write+0x225/0x570 fs/ext4/super.c:7105 write_blk fs/quota/quota_tree.c:64 [inline] get_free_dqblk+0x34a/0x6d0 fs/quota/quota_tree.c:130 do_insert_tree+0x26b/0x1aa0 fs/quota/quota_tree.c:340 do_insert_tree+0x722/0x1aa0 fs/quota/quota_tree.c:375 do_insert_tree+0x722/0x1aa0 fs/quota/quota_tree.c:375 do_insert_tree+0x722/0x1aa0 fs/quota/quota_tree.c:375 dq_insert_tree fs/quota/quota_tree.c:401 [inline] qtree_write_dquot+0x3b6/0x530 fs/quota/quota_tree.c:420 v2_write_dquot+0x11b/0x190 fs/quota/quota_v2.c:358 dquot_acquire+0x348/0x670 fs/quota/dquot.c:444 ext4_acquire_dquot+0x2dc/0x400 fs/ext4/super.c:6740 dqget+0x999/0xdc0 fs/quota/dquot.c:914 __dquot_initialize+0x3d0/0xcf0 fs/quota/dquot.c:1492 ext4_process_orphan+0x57/0x2d0 fs/ext4/orphan.c:329 ext4_orphan_cleanup+0xb60/0x1340 fs/ext4/orphan.c:474 __ext4_fill_super fs/ext4/super.c:5516 [inline] ext4_fill_super+0x81cd/0x8700 fs/ext4/super.c:5644 get_tree_bdev+0x400/0x620 fs/super.c:1282 vfs_get_tree+0x88/0x270 fs/super.c:1489 do_new_mount+0x289/0xad0 fs/namespace.c:3145 do_mount fs/namespace.c:3488 [inline] __do_sys_mount fs/namespace.c:3697 [inline] __se_sys_mount+0x2d3/0x3c0 fs/namespace.c:3674 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Add some debug information: mb_find_extent: mb_find_extent block=41, order=0 needed=64 next=0 ex=0/41/1@3735929054 64 64 7 block_bitmap: ff 3f 0c 00 fc 01 00 00 d2 3d 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff Acctually, blocks per group is 64, but block bitmap indicate at least has 128 blocks. Now, ext4_validate_block_bitmap() didn't check invalid block's bitmap if set. To resolve above issue, add check like fsck "Padding at end of block bitmap is not set".

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2025-09-17	—	0.02%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2025-09-17

—

0.02%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
5.5	3.1	MEDIUM	`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H` Click to expand Attack vector (AV:L) They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:L) A normal user session is enough; they don’t have to be admin. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	1.8	3.6	[email protected]
5.5	3.1	MEDIUM	`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H` Click to expand Attack vector (AV:L) They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:L) A normal user session is enough; they don’t have to be admin. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	1.8	3.6	134c704f-9b21-4f2e-91b3-4a467353bcc0

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

5.5

3.1

MEDIUM

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

Attack vector (AV:L): They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L): A normal user session is enough; they don’t have to be admin.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

1.8

3.6

[email protected]

5.5

3.1

MEDIUM

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

Attack vector (AV:L): They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L): A normal user session is enough; they don’t have to be admin.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

1.8

3.6

134c704f-9b21-4f2e-91b3-4a467353bcc0

OS Trackers for CVE-2023-53317

vendor	priority	summary	link
`debian`	not yet assigned	CVE-2023-53317 not yet assigned priority: Debian including 1 source packages (linux), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5.	https://security-tracker.debian.org/tracker/CVE-2023-53317
`redhat`	medium	—	https://access.redhat.com/security/cve/CVE-2023-53317
`suse`	medium	—	https://www.suse.com/security/cve/CVE-2023-53317/
`ubuntu`	medium	CVE-2023-53317 medium priority: Ubuntu including 158 source packages (linux, linux-allwinner-5.19, …), 1414 status rows across 9 suites (bionic, focal, jammy, noble, plucky, questing, trusty, upstream, xenial): DNE 1017, ignored 162, released 138, not-affected 76, needed 20, needs-triage 1.	https://ubuntu.com/security/CVE-2023-53317

Affected software / configurations for CVE-2023-53317

Vendor	Product	Version	Raw CPE
linux	linux_kernel	< 4.19.283	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 4.20, < 5.4.243	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 5.5, < 5.10.180	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 5.11, < 5.15.112	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 5.16, < 6.1.29	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 6.2, < 6.2.16	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 6.3, < 6.3.3	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	6.4	cpe:2.3:o:linux:linux_kernel:6.4:rc1::::::

References for CVE-2023-53317

URL	Tags
https://git.kernel.org/stable/c/1b90fbc7590124c57a2e590de7fd07eba26606f1	Patch
https://git.kernel.org/stable/c/5d356d902e9d5b1aaaaf2326d365340fa8a90c1b	Patch
https://git.kernel.org/stable/c/775b00ba23f6f916fe2ac60c5ff7fd0fe4f28d0d	Patch
https://git.kernel.org/stable/c/d55e76e11592a1d18a179c7fd34ca1b52632beb3	Patch
https://git.kernel.org/stable/c/dba62fa84a8eac44a53a2862de8a40e5bdfa0ae3	Patch
https://git.kernel.org/stable/c/dd45e536f47a82e0a405f9a4b6c7ceb367171ee9	Patch
https://git.kernel.org/stable/c/e4d503c956a744cb59e509ca5f134cfad423c7a3	Patch
https://git.kernel.org/stable/c/fa08a7b61dff8a4df11ff1e84abfc214b487caf7	Patch

URL

CVE-2023-53317 | ext4: fix WARNING in mb_find_extent

Exploit prediction scoring system (EPSS) score for CVE-2023-53317

Common vulnerability scoring system (CVSS) metrics for CVE-2023-53317

Weakness enumeration for CVE-2023-53317

OS Trackers for CVE-2023-53317

Affected software / configurations for CVE-2023-53317

References for CVE-2023-53317