In the Linux kernel, the following vulnerability has been resolved:
ext4: fix uninititialized value in 'ext4_evict_inode'
Syzbot found the following issue:
=====================================================
BUG: KMSAN: uninit-value in ext4_evict_inode+0xdd/0x26b0 fs/ext4/inode.c:180
ext4_evict_inode+0xdd/0x26b0 fs/ext4/inode.c:180
evict+0x365/0x9a0 fs/inode.c:664
iput_final fs/inode.c:1747 [inline]
iput+0x985/0xdd0 fs/inode.c:1773
__ext4_new_inode+0xe54/0x7ec0 fs/ext4/ialloc.c:1361
ext4_mknod+0x376/0x840 fs/ext4/namei.c:2844
vfs_mknod+0x79d/0x830 fs/namei.c:3914
do_mknodat+0x47d/0xaa0
__do_sys_mknodat fs/namei.c:3992 [inline]
__se_sys_mknodat fs/namei.c:3989 [inline]
__ia32_sys_mknodat+0xeb/0x150 fs/namei.c:3989
do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
__do_fast_syscall_32+0xa2/0x100 arch/x86/entry/common.c:178
do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:246
entry_SYSENTER_compat_after_hwframe+0x70/0x82
Uninit was created at:
__alloc_pages+0x9f1/0xe80 mm/page_alloc.c:5578
alloc_pages+0xaae/0xd80 mm/mempolicy.c:2285
alloc_slab_page mm/slub.c:1794 [inline]
allocate_slab+0x1b5/0x1010 mm/slub.c:1939
new_slab mm/slub.c:1992 [inline]
___slab_alloc+0x10c3/0x2d60 mm/slub.c:3180
__slab_alloc mm/slub.c:3279 [inline]
slab_alloc_node mm/slub.c:3364 [inline]
slab_alloc mm/slub.c:3406 [inline]
__kmem_cache_alloc_lru mm/slub.c:3413 [inline]
kmem_cache_alloc_lru+0x6f3/0xb30 mm/slub.c:3429
alloc_inode_sb include/linux/fs.h:3117 [inline]
ext4_alloc_inode+0x5f/0x860 fs/ext4/super.c:1321
alloc_inode+0x83/0x440 fs/inode.c:259
new_inode_pseudo fs/inode.c:1018 [inline]
new_inode+0x3b/0x430 fs/inode.c:1046
__ext4_new_inode+0x2a7/0x7ec0 fs/ext4/ialloc.c:959
ext4_mkdir+0x4d5/0x1560 fs/ext4/namei.c:2992
vfs_mkdir+0x62a/0x870 fs/namei.c:4035
do_mkdirat+0x466/0x7b0 fs/namei.c:4060
__do_sys_mkdirat fs/namei.c:4075 [inline]
__se_sys_mkdirat fs/namei.c:4073 [inline]
__ia32_sys_mkdirat+0xc4/0x120 fs/namei.c:4073
do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
__do_fast_syscall_32+0xa2/0x100 arch/x86/entry/common.c:178
do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:246
entry_SYSENTER_compat_after_hwframe+0x70/0x82
CPU: 1 PID: 4625 Comm: syz-executor.2 Not tainted 6.1.0-rc4-syzkaller-62821-gcb231e2f67ec #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
=====================================================
Now, 'ext4_alloc_inode()' didn't init 'ei->i_flags'. If new inode failed
before set 'ei->i_flags' in '__ext4_new_inode()', then do 'iput()'. As after
6bc0d63dad7f commit will access 'ei->i_flags' in 'ext4_evict_inode()' which
will lead to access uninit-value.
To solve above issue just init 'ei->i_flags' in 'ext4_alloc_inode()'.
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (7.8): severity, escalated by confirmed exploitation. This CVE's 7.8 is its impact severity (EG Severity), not escalated.
- EG Severity
- 7.8 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-20). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines.
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it