Answer in brief
CVE-2021-47656 records a High severity (CVSS 7.8) vulnerability in jffs2: fix use-after-free in jffs2_clear_xattr_subsystem. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=aa98d7cf59b5b0764d3502662053489585faf2fe <9150cb625b46f68d524f4cfd491f1aafc23e10a9 || >=aa98d7cf59b5b0764d3502662053489585faf2fe <3bd2454162ec6bbb5503233c804fce6e4b6dcec5 || >=aa98d7cf59b5b0764d3502662053489585faf2fe <c3b07c875fa8f906f932976460fd14798596f101 || >=aa98d7cf59b5b0764d3502662053489585faf2fe <30bf7244acf32f19cb722c39f7bc1c2a9f300422 || >=aa98d7cf59b5b0764d3502662053489585faf2fe <7bb7428dd73991bf4b3a7a61b493ca50046c2b13 || >=aa98d7cf59b5b0764d3502662053489585faf2fe <7a75740206af5f17e9f3efa384211cba70213da1 || >=aa98d7cf59b5b0764d3502662053489585faf2fe <22327bd7988f21de3a53c1373f3b81542bfe1f44 || >=aa98d7cf59b5b0764d3502662053489585faf2fe <8c0f024f29e055840a5a89fe23b96ae3f921afed || >=aa98d7cf59b5b0764d3502662053489585faf2fe <4c7c44ee1650677fbe89d86edbad9497b7679b5c | 9150cb625b46f68d524f4cfd491f1aafc23e10a9, 3bd2454162ec6bbb5503233c804fce6e4b6dcec5, c3b07c875fa8f906f932976460fd14798596f101, 30bf7244acf32f19cb722c39f7bc1c2a9f300422, 7bb7428dd73991bf4b3a7a61b493ca50046c2b13, 7a75740206af5f17e9f3efa384211cba70213da1, 22327bd7988f21de3a53c1373f3b81542bfe1f44, 8c0f024f29e055840a5a89fe23b96ae3f921afed, 4c7c44ee1650677fbe89d86edbad9497b7679b5c |
| Linux/Linuxgeneric | 2.6.18 | Not reported |
Published upstream
Feb 26, 2025
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 4, 2026
In the Linux kernel, the following vulnerability has been resolved: jffs2: fix use-after-free in jffs2_clear_xattr_subsystem When we mount a jffs2 image, assume that the first few blocks of the image are normal and contain at least one xattr-related inode, but the next block is abnormal. As a result, an error is returned in jffs2_scan_eraseblock(). jffs2_clear_xattr_subsystem() is then called in jffs2_build_filesystem() and then again in jffs2_do_fill_super(). Finally we can observe the following report: ================================================================== BUG: KASAN: use-after-free in jffs2_clear_xattr_subsystem+0x95/0x6ac Read of size 8 at addr ffff8881243384e0 by task mount/719 Call Trace: dump_stack+0x115/0x16b jffs2_clear_xattr_subsystem+0x95/0x6ac jffs2_do_fill_super+0x84f/0xc30 jffs2_fill_super+0x2ea/0x4c0 mtd_get_sb+0x254/0x400 mtd_get_sb_by_nr+0x4f/0xd0 get_tree_mtd+0x498/0x840 jffs2_get_tree+0x25/0x30 vfs_get_tree+0x8d/0x2e0 path_mount+0x50f/0x1e50 do_mount+0x107/0x130 __se_sys_mount+0x1c5/0x2f0 __x64_sys_mount+0xc7/0x160 do_syscall_64+0x45/0x70 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Allocated by task 719: kasan_save_stack+0x23/0x60 __kasan_kmalloc.constprop.0+0x10b/0x120 kasan_slab_alloc+0x12/0x20 kmem_cache_alloc+0x1c0/0x870 jffs2_alloc_xattr_ref+0x2f/0xa0 jffs2_scan_medium.cold+0x3713/0x4794 jffs2_do_mount_fs.cold+0xa7/0x2253 jffs2_do_fill_super+0x383/0xc30 jffs2_fill_super+0x2ea/0x4c0 [...] Freed by task 719: kmem_cache_free+0xcc/0x7b0 jffs2_free_xattr_ref+0x78/0x98 jffs2_clear_xattr_subsystem+0xa1/0x6ac jffs2_do_mount_fs.cold+0x5e6/0x2253 jffs2_do_fill_super+0x383/0xc30 jffs2_fill_super+0x2ea/0x4c0 [...] The buggy address belongs to the object at ffff8881243384b8 which belongs to the cache jffs2_xattr_ref of size 48 The buggy address is located 40 bytes inside of 48-byte region [ffff8881243384b8, ffff8881243384e8) [...] ================================================================== The triggering of the BUG is shown in the following stack: ----------------------------------------------------------- jffs2_fill_super jffs2_do_fill_super jffs2_do_mount_fs jffs2_build_filesystem jffs2_scan_medium jffs2_scan_eraseblock <--- ERROR jffs2_clear_xattr_subsystem <--- free jffs2_clear_xattr_subsystem <--- free again ----------------------------------------------------------- An error is returned in jffs2_do_mount_fs(). If the error is returned by jffs2_sum_init(), the jffs2_clear_xattr_subsystem() does not need to be executed. If the error is returned by jffs2_build_filesystem(), the jffs2_clear_xattr_subsystem() also does not need to be executed again. So move jffs2_clear_xattr_subsystem() from 'out_inohash' to 'out_root' to fix this UAF problem.
Quoted source text, attributed separately from HOL analysis.