CVE-2025-21712: Linux kernel · md/md-bitmap: Synchronize bitmap_get_stats() with bitmap lifetime
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.8 High · fixed in 5.15.0-186.196~20.04.1 : patch Linux kernel soon.
Data as of 26 Oct 2026, 12:55 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 12% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.15.0-186.196~20.04.1, 5.15.0-184.194~20.04.1, 5.15.0-1064.66~20.04.1 +43
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 27 Feb 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux@6.8.0-78.78?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws@6.8.0-1035.37?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure@6.8.0-1034.39?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azure-6.11pkg:deb/ubuntu/linux-azure-6.11@6.11.0-1015.15~24.04.1?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azure-nvidiapkg:deb/ubuntu/linux-azure-nvidia@6.8.0-1022.23?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp@6.8.0-1036.38?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
In the Linux kernel, the following vulnerability has been resolved: md/md-bitmap: Synchronize bitmap_get_stats() with bitmap lifetime After commit ec6bb299c7c3 ("md/md-bitmap: add 'sync_size' into struct md_bitmap_stats"), following panic is reported: Oops: general protection fault, probably for non-canonical address RIP: 0010:bitmap_get_stats+0x2b/0xa0 Call Trace: <TASK> md_seq_show+0x2d2/0x5b0 seq_read_iter+0x2b9/0x470 seq_read+0x12f/0x180 proc_reg_read+0x57/0xb0 vfs_read+0xf6/0x380 ksys_read+0x6c/0xf0 do_syscall_64+0x82/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e Root cause is that bitmap_get_stats() can be called at anytime if mddev is still there, even if bitmap is destroyed, or not fully initialized. Deferenceing bitmap in this case can crash the kernel. Meanwhile, the above commit start to deferencing bitmap->storage, make the problem easier to trigger. Fix the problem by protecting bitmap_get_stats() with bitmap_info.mutex.
References
- ubuntu.com/security/CVE-2025-21712 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-21712 (opens in a new tab)
- git.kernel.org/linus/8d28d0ddb986f56920ac97ae704cc3340a699a30 (opens in a new tab)
- git.kernel.org/stable/c/237e19519c8ff6949f0ef57c4a0243f5b2b0fa18 (opens in a new tab)
- git.kernel.org/stable/c/4e9316eee3885bfb311b4759513f2ccf37891c09 (opens in a new tab)
- git.kernel.org/stable/c/52848a095b55a302af92f52ca0de5b3112059bb8 (opens in a new tab)
- git.kernel.org/stable/c/8d28d0ddb986f56920ac97ae704cc3340a699a30 (opens in a new tab)
- ubuntu.com/security/notices/USN-7521-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7521-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7521-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7703-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7703-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7703-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7719-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7703-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-7737-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8575-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8576-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8575-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8576-2 (opens in a new tab)