high CVSS 7.8

CVE-2021-47600·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: dm btree remove: fix use after free in rebalance_children() Move dm_tm_unlock() after dm_tm_dec().

Severity
high
Software
Kernel
Fixed in
5.15.11
Published
2024-06-19

Affected versions

From: 5.11

Until: 5.15.11

Fixed in: 5.15.11

How to fix this CVE

Update your Linux kernel to version 5.15.11 or later to remediate CVE-2021-47600, a memory corruption vulnerability in the device mapper btree removal logic. This flaw allows local privileged users to cause a denial of service or potentially escalate privileges by triggering a use-after-free condition during btree rebalancing operations. Apply the patch immediately if your system is running kernel versions 5.11 through 5.15.10.

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; if it falls within 5.11.x to 5.15.10, your system is vulnerable
  2. Verify device mapper btree usage by checking if dm-related modules are loaded: 'lsmod | grep dm'
  3. Search kernel logs for btree rebalancing errors: 'journalctl -u kernel | grep -i "btree\|rebalance"'
  4. After patching, run 'uname -r' again and confirm the kernel version is 5.15.11 or later

FAQ

What is CVE-2021-47600?

CVE-2021-47600 is a use-after-free vulnerability in the Linux kernel's device mapper btree removal function that occurs when memory is accessed after being freed during rebalancing operations, potentially allowing local privilege escalation.

Is CVE-2021-47600 being actively exploited?

No, this vulnerability is not listed on the CISA Known Exploited Vulnerabilities (KEV) catalog and no public exploits are currently available, though the high CVSS score warrants prompt patching.

What versions of Kernel are affected by CVE-2021-47600?

Linux kernel versions 5.11.0 through 5.15.10 are vulnerable; version 5.15.11 and later include the fix.

How do I check if my server is vulnerable to CVE-2021-47600?

Run 'uname -r' and verify the output; if it shows a kernel version between 5.11 and 5.15.10 (inclusive), your system requires the patch.

Does Defensia detect CVE-2021-47600?

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-2021-47600 will appear in your dashboard with remediation steps.

Related Kernel CVEs

CVE-2024-42256CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: cifs: Fix server re-repick on subrequest retry When a subrequest is marked for needing retry, netfs will call cifs_prepare_write() which will make cifs repick the server for the op before renegotiating credits; it then calls cifs_issue_write() which invokes smb2_async_writev() - which re-repicks the server. If a different server is then selected, this causes the increment of server->in_flight to happen against one record and the decrement to happen against another, leading to misaccounting. Fix this by just removing the repick code in smb2_async_writev(). As this is only called from netfslib-driven code, cifs_prepare_write() should always have been called first, and so server should never be NULL and the preparatory step is repeated in the event that we do a retry. The problem manifests as a warning looking something like: WARNING: CPU: 4 PID: 72896 at fs/smb/client/smb2ops.c:97 smb2_add_credits+0x3f0/0x9e0 [cifs] ... RIP: 0010:smb2_add_credits+0x3f0/0x9e0 [cifs] ... smb2_writev_callback+0x334/0x560 [cifs] cifs_demultiplex_thread+0x77a/0x11b0 [cifs] kthread+0x187/0x1d0 ret_from_fork+0x34/0x60 ret_from_fork_asm+0x1a/0x30 Which may be triggered by a number of different xfstests running against an Azure server in multichannel mode. generic/249 seems the most repeatable, but generic/215, generic/249 and generic/308 may also show it.
CVE-2024-36031CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: keys: Fix overwrite of key expiration on instantiation The expiry time of a key is unconditionally overwritten during instantiation, defaulting to turn it permanent. This causes a problem for DNS resolution as the expiration set by user-space is overwritten to TIME64_MAX, disabling further DNS updates. Fix this by restoring the condition that key_set_expiry is only called when the pre-parser sets a specific expiry.
CVE-2024-38612CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: ipv6: sr: fix invalid unregister error path The error path of seg6_init() is wrong in case CONFIG_IPV6_SEG6_LWTUNNEL is not defined. In that case if seg6_hmac_init() fails, the genl_unregister_family() isn't called. This issue exist since commit 46738b1317e1 ("ipv6: sr: add option to control lwtunnel support"), and commit 5559cea2d5aa ("ipv6: sr: fix possible use-after-free and null-ptr-deref") replaced unregister_pernet_subsys() with genl_unregister_family() in this error path.
CVE-2024-38623CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: fs/ntfs3: Use variable length array instead of fixed size Should fix smatch warning: ntfs_set_label() error: __builtin_memcpy() 'uni->name' too small (20 vs 256)
CVE-2022-48716CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: ASoC: codecs: wcd938x: fix incorrect used of portid Mixer controls have the channel id in mixer->reg, which is not same as port id. port id should be derived from chan_info array. So fix this. Without this, its possible that we could corrupt struct wcd938x_sdw_priv by accessing port_map array out of range with channel id instead of port id.

References

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