In the Linux kernel, the following vulnerability has been resolved:
jfs: reject on-disk inodes of an unsupported type
Syzbot has reported the following BUG:
kernel BUG at fs/inode.c:668!
Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 3 UID: 0 PID: 139 Comm: jfsCommit Not tainted 6.12.0-rc4-syzkaller-00085-g4e46774408d9 #0
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014
RIP: 0010:clear_inode+0x168/0x190
Code: 4c 89 f7 e8 ba fe e5 ff e9 61 ff ff ff 44 89 f1 80 e1 07 80 c1 03 38 c1 7c c1 4c 89 f7 e8 90 ff e5 ff eb b7
0b e8 01 5d 7f ff 90 0f 0b e8 f9 5c 7f ff 90 0f 0b e8 f1 5c 7f
RSP: 0018:ffffc900027dfae8 EFLAGS: 00010093
RAX: ffffffff82157a87 RBX: 0000000000000001 RCX: ffff888104d4b980
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900027dfc90 R08: ffffffff82157977 R09: fffff520004fbf38
R10: dffffc0000000000 R11: fffff520004fbf38 R12: dffffc0000000000
R13: ffff88811315bc00 R14: ffff88811315bda8 R15: ffff88811315bb80
FS: 0000000000000000(0000) GS:ffff888135f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005565222e0578 CR3: 0000000026ef0000 CR4: 00000000000006f0
Call Trace:
? __die_body+0x5f/0xb0
? die+0x9e/0xc0
? do_trap+0x15a/0x3a0
? clear_inode+0x168/0x190
? do_error_trap+0x1dc/0x2c0
? clear_inode+0x168/0x190
? __pfx_do_error_trap+0x10/0x10
? report_bug+0x3cd/0x500
? handle_invalid_op+0x34/0x40
? clear_inode+0x168/0x190
? exc_invalid_op+0x38/0x50
? asm_exc_invalid_op+0x1a/0x20
? clear_inode+0x57/0x190
? clear_inode+0x167/0x190
? clear_inode+0x168/0x190
? clear_inode+0x167/0x190
jfs_evict_inode+0xb5/0x440
? __pfx_jfs_evict_inode+0x10/0x10
evict+0x4ea/0x9b0
? __pfx_evict+0x10/0x10
? iput+0x713/0xa50
txUpdateMap+0x931/0xb10
? __pfx_txUpdateMap+0x10/0x10
jfs_lazycommit+0x49a/0xb80
? _raw_spin_unlock_irqrestore+0x8f/0x140
? lockdep_hardirqs_on+0x99/0x150
? __pfx_jfs_lazycommit+0x10/0x10
? __pfx_default_wake_function+0x10/0x10
? __kthread_parkme+0x169/0x1d0
? __pfx_jfs_lazycommit+0x10/0x10
kthread+0x2f2/0x390
? __pfx_jfs_lazycommit+0x10/0x10
? __pfx_kthread+0x10/0x10
ret_from_fork+0x4d/0x80
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1a/0x30
This happens when 'clear_inode()' makes an attempt to finalize an underlying
JFS inode of unknown type. According to JFS layout description from
https://jfs.sourceforge.net/project/pub/jfslayout.pdf, inode types from 5 to
15 are reserved for future extensions and should not be encountered on a valid
filesystem. So add an extra check for valid inode type in 'copy_from_dinode()'.
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (5.5): severity, escalated by confirmed exploitation. This CVE's 5.5 is its impact severity (EG Severity), not escalated.
- EG Severity
- 5.5 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-24). 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, and whom BOD 26-04 binds: 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.
The score's inputs: 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