CVE-2026-53304
Status: AnalyzedMedium (5.5)—
In the Linux kernel, the following vulnerability has been resolved:
scsi: sg: Resolve soft lockup issue when opening /dev/sgX
The parameter def_reserved_size defines the default buffer size reserved for each Sg_fd and should be restricted to a range between 0 and 1,048,576 (see https://tldp.org/HOWTO/SCSI-Generic-HOWTO/proc.html). Although the function sg_proc_write_dressz enforces this limit, it is possible to bypass it by directly modifying the module parameter as shown below, which then causes a soft lockup:
echo -1 > /sys/module/sg/parameters/def_reserved_size exec 4<> /dev/sg0
watchdog: BUG: soft lockup - CPU#5 stuck for 26 seconds! [bash:537] Modules loaded: CPU: 5 UID: 0 PID: 537 Command: bash, kernel version 6.19.0-rc3+ #134, PREEMPT disabled Hardware: QEMU Standard PC (i440FX + PIIX, 1996), BIOS version 1.16.1-2.fc37 dated 04/01/2014 ...
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Call Trace:
The fix is to use module_param_cb to validate and reject invalid values assigned to def_reserved_size.
Technical details traces, logs and code from the original report
sg_build_reserve+0x5c/0xa0 sg_add_sfp+0x168/0x270 sg_open+0x16e/0x340 chrdev_open+0xbe/0x230 do_dentry_open+0x175/0x480 vfs_open+0x34/0xf0 do_open+0x265/0x3d0 path_openat+0x110/0x290 do_filp_open+0xc3/0x170 do_sys_openat2+0x71/0xe0 __x64_sys_openat+0x6d/0xa0 do_syscall_64+0x62/0x310 entry_SYSCALL_64_after_hwframe+0x76/0x7e
CVSS
- Version: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Base score: 5.5
Exploitation probability (EPSS)
- Probability of exploitation in the next 30 days: 0.13%
- Percentile among all scored CVEs: 2
- Score date: 10/3/2026
EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).
Affected technologies (1)
CWEs
- CWE-667
References
- https://git.kernel.org/stable/c/1afd963fcd963db0dc5d47df6dfcf010c9c4647e
- https://git.kernel.org/stable/c/3d74e0654ac908c65a8f20373091826fe43b1363
- https://git.kernel.org/stable/c/9676ca7b1ef31a3a65b3e61e7ce3b54ce7364202
- https://git.kernel.org/stable/c/c47ccfb3d80dfed522ca06a5954ac97488d78c5a
- https://git.kernel.org/stable/c/c5f4a211e82d04ccc1809311322c47023bbe66e2
- https://git.kernel.org/stable/c/d06a310b45e153872033dd0cf19d5a2279121099
- https://git.kernel.org/stable/c/fe671d3c84ffb1b763d590c25195755adeaadaba
- https://git.kernel.org/stable/c/feade299e932967de27519338d41de348fb5b061
Raw JSON (NVD)
Show
{
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"integrityImpact": "NONE",
"userInteraction": "NONE",
"attackComplexity": "LOW",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nscsi: sg: Resolve soft lockup issue when opening /dev/sgX\n\nThe parameter def_reserved_size defines the default buffer size reserved\nfor each Sg_fd and should be restricted to a range between 0 and 1,048,576\n(see https://tldp.org/HOWTO/SCSI-Generic-HOWTO/proc.html). Although the\nfunction sg_proc_write_dressz enforces this limit, it is possible to bypass\nit by directly modifying the module parameter as shown below, which then\ncauses a soft lockup:\n\necho -1 > /sys/module/sg/parameters/def_reserved_size\nexec 4<> /dev/sg0\n\nwatchdog: BUG: soft lockup - CPU#5 stuck for 26 seconds! [bash:537]\nModules loaded:\nCPU: 5 UID: 0 PID: 537 Command: bash, kernel version 6.19.0-rc3+ #134,\nPREEMPT disabled\nHardware: QEMU Standard PC (i440FX + PIIX, 1996), BIOS version\n1.16.1-2.fc37 dated 04/01/2014\n...\nCall Trace:\n\n sg_build_reserve+0x5c/0xa0\n sg_add_sfp+0x168/0x270\n sg_open+0x16e/0x340\n chrdev_open+0xbe/0x230\n do_dentry_open+0x175/0x480\n vfs_open+0x34/0xf0\n do_open+0x265/0x3d0\n path_openat+0x110/0x290\n do_filp_open+0xc3/0x170\n do_sys_openat2+0x71/0xe0\n __x64_sys_openat+0x6d/0xa0\n do_syscall_64+0x62/0x310\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nThe fix is to use module_param_cb to validate and reject invalid values\nassigned to def_reserved_size."
}
],
"lastModified": "2026-07-06T20:24:15.403",
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