CVE-2025-21772
Published: 27 February 2025
Summary
CVE-2025-21772 is a high-severity Out-of-bounds Write (CWE-787) vulnerability in Linux Linux Kernel. Its CVSS base score is 7.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 2.7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and SI-16 (Memory Protection).
Deeper analysis
CVE-2025-21772 is a vulnerability in the Linux kernel's MAC partition table parsing code, stemming from improper handling of malformed or bogus partition tables. Specifically, it addresses issues such as failing to call put_dev_sector() after a successful read_part_sector() during bailout for invalid partoffset values, processing absurd sector sizes (e.g., 0xfff bytes) that cause partition entries to straddle sector boundaries and lead to out-of-bounds memory access, and assuming NUL-terminated strings in partition names by using strlen() and strcmp() instead of safer strnlen() and strncmp(). This results in a CWE-787 (Out-of-bounds Write) condition with a CVSS v3.1 base score of 7.8 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).
A local attacker with low privileges (PR:L) can exploit this vulnerability with low complexity by presenting a crafted disk image or device with a malicious MAC partition table to a system during partition probing. Successful exploitation grants high-impact confidentiality, integrity, and availability consequences, potentially allowing arbitrary code execution, data corruption, or denial of service through out-of-bounds memory writes.
Mitigation requires applying the upstream kernel patches from the provided stable branch commits, including 213ba5bd81b7e97ac6e6190b8f3bc6ba76123625, 27a39d006f85e869be68c1d5d2ce05e5d6445bf5, 40a35d14f3c0dc72b689061ec72fc9b193f37d1f, 6578717ebca91678131d2b1f4ba4258e60536e9f, and 7fa9706722882f634090bfc9af642bf9ed719e27, which resolve the parsing flaws and prevent the identified memory safety issues.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-5153
Vulnerability details
In the Linux kernel, the following vulnerability has been resolved: partitions: mac: fix handling of bogus partition table Fix several issues in partition probing: - The bailout for a bad partoffset must use put_dev_sector(), since the preceding read_part_sector() succeeded. -…
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If the partition table claims a silly sector size like 0xfff bytes (which results in partition table entries straddling sector boundaries), bail out instead of accessing out-of-bounds memory. - We must not assume that the partition table contains proper NUL termination - use strnlen() and strncmp() instead of strlen() and strcmp().
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Kernel out-of-bounds write in partition table parsing enables local arbitrary code execution and privilege escalation.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Mandates validation of inputs from MAC partition tables, including sector sizes, offsets, and strings using bounded functions, directly preventing out-of-bounds memory access from malformed data.
Requires timely patching of the Linux kernel flaw with upstream commits that fix improper bailout, absurd sector size handling, and unsafe string operations in MAC partition parsing.
Enforces memory protections such as non-executable regions and bounds checking to mitigate exploitation of out-of-bounds writes triggered by bogus partition tables.