CVE-2026-53039
Linux Kernel 2.6.25 – 5.10.258
Raw vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). EPSS scores by FIRST (EPSS SIG), generated by Empirical Security. Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2026-53039 is a medium-severity Reachable Assertion (CWE-617) vulnerability in Linux Kernel. Its CVSS base score is 5.5 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Defense Impairment (T1687); ranked at the 5th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-8 (Security and Privacy Engineering Principles) — see the control section below for these in your framework.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-38907
Vulnerability Data
In the Linux kernel, the following vulnerability has been resolved: ocfs2: validate group add input before caching [BUG] OCFS2_IOC_GROUP_ADD can trigger a BUG_ON in ocfs2_set_new_buffer_uptodate(): kernel BUG at fs/ocfs2/uptodate.c:509! Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI RIP: 0010:ocfs2_set_new_buffer_uptodate+0x194/0x1e0 fs/ocfs2/uptodate.c:509…
more
Code: ffffe88f 42b9fe4c 89e64889 dfe8b4df Call Trace: ocfs2_group_add+0x3f1/0x1510 fs/ocfs2/resize.c:507 ocfs2_ioctl+0x309/0x6e0 fs/ocfs2/ioctl.c:887 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0x197/0x1e0 fs/ioctl.c:583 x64_sys_call+0x1144/0x26a0 arch/x86/include/generated/asm/syscalls_64.h:17 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x93/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7bbfb55a966d [CAUSE] ocfs2_group_add() calls ocfs2_set_new_buffer_uptodate() on a user-controlled group block before ocfs2_verify_group_and_input() validates that block number. That helper is only valid for newly allocated metadata and asserts that the block is not already present in the chosen metadata cache. The code also uses INODE_CACHE(inode) even though the group descriptor belongs to main_bm_inode and later journal accesses use that cache context instead. [FIX] Validate the on-disk group descriptor before caching it, then add it to the metadata cache tracked by INODE_CACHE(main_bm_inode). Keep the validation failure path separate from the later cleanup path so we only remove the buffer from that cache after it has actually been inserted. This keeps the group buffer lifetime consistent across validation, journaling, and cleanup.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation finds reachable assertions during development.
Security engineering principles discourage use of assertions for handling untrusted input.
Validating untrusted inputs structurally prevents attacker data from reaching and triggering assertions.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly prevent unsafe assertions from being coded in reachable paths.
Runtime monitoring of software can detect assertion-triggered crashes as adverse events.
Vulnerability identification processes can discover and record reachable-assertion flaws before deployment.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing in development can detect reachable assertions before release, reducing the likelihood of exploitation.
Secure coding standards explicitly ban the use of assert() or equivalent statements that can be triggered by external input.