high CVSS 7.8 EPSS <0.1%

CVE-2022-48847·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: watch_queue: Fix filter limit check In watch_queue_set_filter(), there are a couple of places where we check that the filter type value does not exceed what the type_filter bitmap can hold. One place calculates the number of bits by: if (tf[i].type >= sizeof(wfilter->type_filter) * 8) which is fine, but the second does: if (tf[i].type >= sizeof(wfilter->type_filter) * BITS_PER_LONG) which is not. This can lead to a couple of out-of-bounds writes due to a too-large type: (1) __set_bit() on wfilter->type_filter (2) Writing more elements in wfilter->filters[] than we allocated. Fix this by just using the proper WATCH_TYPE__NR instead, which is the number of types we actually know about. The bug may cause an oops looking something like: BUG: KASAN: slab-out-of-bounds in watch_queue_set_filter+0x659/0x740 Write of size 4 at addr ffff88800d2c66bc by task watch_queue_oob/611 ... Call Trace: <TASK> dump_stack_lvl+0x45/0x59 print_address_description.constprop.0+0x1f/0x150 ... kasan_report.cold+0x7f/0x11b ... watch_queue_set_filter+0x659/0x740 ... __x64_sys_ioctl+0x127/0x190 do_syscall_64+0x43/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae Allocated by task 611: kasan_save_stack+0x1e/0x40 __kasan_kmalloc+0x81/0xa0 watch_queue_set_filter+0x23a/0x740 __x64_sys_ioctl+0x127/0x190 do_syscall_64+0x43/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae The buggy address belongs to the object at ffff88800d2c66a0 which belongs to the cache kmalloc-32 of size 32 The buggy address is located 28 bytes inside of 32-byte region [ffff88800d2c66a0, ffff88800d2c66c0)

Severity
high
Software
Kernel
Fixed in
5.16.15
Published

How likely is exploitation

FIRST's Exploit Prediction Scoring System puts the probability of this CVE being exploited in the next 30 days at <0.1% — higher than 10% of all published CVEs. EPSS is an independent forecast of exploitation, not a severity rating: it says nothing about how much damage a successful attack does, which is what a CVSS score measures.

Read the two together. CVE-2022-48847 scores 7.8 on CVSS, so a successful attack would be serious — but at <0.1%, almost nobody is currently attempting it. That is a different situation from a flaw under mass exploitation, and it is usually the difference between patching on your next maintenance window and patching tonight.

Affected versions

From: 5.16

Until: 5.16.15

Fixed in: 5.16.15

How to fix this CVE

Update your Linux kernel to version 5.16.15 or later to patch a critical out-of-bounds memory write vulnerability in the watch_queue subsystem. This flaw allows local attackers with low privileges to corrupt kernel memory and potentially crash the system. Apply the update immediately if you are running kernel versions 5.16.0 through 5.16.14.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Run 'uname -r' to check your current kernel version and verify if it falls within the affected range (5.16.0 to 5.16.14)
  2. Check if watch_queue functionality is enabled by examining '/boot/config-$(uname -r)' for 'CONFIG_WATCH_QUEUE=y'
  3. Search system logs with 'sudo dmesg | grep -i watch_queue' or 'sudo journalctl -u kernel | grep -i watch_queue' for any watch_queue related errors
  4. After applying updates, run 'uname -r' again to confirm the kernel version is now 5.16.15 or higher

FAQ

What is CVE-2022-48847?

CVE-2022-48847 is a kernel vulnerability in the watch_queue filter mechanism that uses incorrect boundary checks, allowing local users to write beyond allocated memory boundaries and trigger kernel crashes or memory corruption.

Is CVE-2022-48847 being actively exploited?

No, this vulnerability is not listed in CISA's Known Exploited Vulnerabilities catalog and no public exploits are currently available, but the high CVSS score (7.8) indicates it should be prioritized for patching.

What versions of Kernel are affected by CVE-2022-48847?

Linux kernel versions 5.16.0 through 5.16.14 are affected; version 5.16.15 and later contain the fix.

How do I check if my server is vulnerable to CVE-2022-48847?

Run 'uname -r' and check if your kernel version is between 5.16.0 and 5.16.14; if so, your system is vulnerable until you apply the latest updates.

Does Defensia detect CVE-2022-48847?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If the Linux kernel is installed on a monitored server, CVE-2022-48847 will appear in your dashboard with remediation steps.

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References

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