In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix to do sanity check on destination blkaddr during recovery
As Wenqing Liu reported in bugzilla:
https://bugzilla.kernel.org/show_bug.cgi?id=216456
loop5: detected capacity change from 0 to 131072
F2FS-fs (loop5): recover_inode: ino = 6, name = hln, inline = 1
F2FS-fs (loop5): recover_data: ino = 6 (i_size: recover) err = 0
F2FS-fs (loop5): recover_inode: ino = 6, name = hln, inline = 1
F2FS-fs (loop5): recover_data: ino = 6 (i_size: recover) err = 0
F2FS-fs (loop5): recover_inode: ino = 6, name = hln, inline = 1
F2FS-fs (loop5): recover_data: ino = 6 (i_size: recover) err = 0
F2FS-fs (loop5): Bitmap was wrongly set, blk:5634
------------[ cut here ]------------
WARNING: CPU: 3 PID: 1013 at fs/f2fs/segment.c:2198
RIP: 0010:update_sit_entry+0xa55/0x10b0 [f2fs]
Call Trace:
f2fs_do_replace_block+0xa98/0x1890 [f2fs]
f2fs_replace_block+0xeb/0x180 [f2fs]
recover_data+0x1a69/0x6ae0 [f2fs]
f2fs_recover_fsync_data+0x120d/0x1fc0 [f2fs]
f2fs_fill_super+0x4665/0x61e0 [f2fs]
mount_bdev+0x2cf/0x3b0
legacy_get_tree+0xed/0x1d0
vfs_get_tree+0x81/0x2b0
path_mount+0x47e/0x19d0
do_mount+0xce/0xf0
__x64_sys_mount+0x12c/0x1a0
do_syscall_64+0x38/0x90
entry_SYSCALL_64_after_hwframe+0x63/0xcd
If we enable CONFIG_F2FS_CHECK_FS config, it will trigger a kernel panic
instead of warning.
The root cause is: in fuzzed image, SIT table is inconsistent with inode
mapping table, result in triggering such warning during SIT table update.
This patch introduces a new flag DATA_GENERIC_ENHANCE_UPDATE, w/ this
flag, data block recovery flow can check destination blkaddr's validation
in SIT table, and skip f2fs_replace_block() to avoid inconsistent status.
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
- 0.2% 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