In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix to do sanity check on total_data_blocks
As Yanming reported in bugzilla:
https://bugzilla.kernel.org/show_bug.cgi?id=215916
The kernel message is shown below:
kernel BUG at fs/f2fs/segment.c:2560!
Call Trace:
allocate_segment_by_default+0x228/0x440
f2fs_allocate_data_block+0x13d1/0x31f0
do_write_page+0x18d/0x710
f2fs_outplace_write_data+0x151/0x250
f2fs_do_write_data_page+0xef9/0x1980
move_data_page+0x6af/0xbc0
do_garbage_collect+0x312f/0x46f0
f2fs_gc+0x6b0/0x3bc0
f2fs_balance_fs+0x921/0x2260
f2fs_write_single_data_page+0x16be/0x2370
f2fs_write_cache_pages+0x428/0xd00
f2fs_write_data_pages+0x96e/0xd50
do_writepages+0x168/0x550
__writeback_single_inode+0x9f/0x870
writeback_sb_inodes+0x47d/0xb20
__writeback_inodes_wb+0xb2/0x200
wb_writeback+0x4bd/0x660
wb_workfn+0x5f3/0xab0
process_one_work+0x79f/0x13e0
worker_thread+0x89/0xf60
kthread+0x26a/0x300
ret_from_fork+0x22/0x30
RIP: 0010:new_curseg+0xe8d/0x15f0
The root cause is: ckpt.valid_block_count is inconsistent with SIT table,
stat info indicates filesystem has free blocks, but SIT table indicates
filesystem has no free segment.
So that during garbage colloection, it triggers panic when LFS allocator
fails to find free segment.
This patch tries to fix this issue by checking consistency in between
ckpt.valid_block_count and block accounted from SIT.
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 2026-10-25). 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