In the Linux kernel, the following vulnerability has been resolved:
ubifs: ubifs_releasepage: Remove ubifs_assert(0) to valid this process
There are two states for ubifs writing pages:
- Dirty, Private
- Not Dirty, Not Private
The normal process cannot go to ubifs_releasepage() which means there
exists pages being private but not dirty. Reproducer[1] shows that it
could occur (which maybe related to [2]) with following process:
PA PB PC
lock(page)[PA]
ubifs_write_end
attach_page_private // set Private
__set_page_dirty_nobuffers // set Dirty
unlock(page)
write_cache_pages[PA]
lock(page)
clear_page_dirty_for_io(page) // clear Dirty
ubifs_writepage
do_truncation[PB]
truncate_setsize
i_size_write(inode, newsize) // newsize = 0
i_size = i_size_read(inode) // i_size = 0
end_index = i_size >> PAGE_SHIFT
if (page->index > end_index)
goto out // jump
out:
unlock(page) // Private, Not Dirty
generic_fadvise[PC]
lock(page)
invalidate_inode_page
try_to_release_page
ubifs_releasepage
ubifs_assert(c, 0)
// bad assertion!
unlock(page)
truncate_pagecache[PB]
Then we may get following assertion failed:
UBIFS error (ubi0:0 pid 1683): ubifs_assert_failed [ubifs]:
UBIFS assert failed: 0, in fs/ubifs/file.c:1513
UBIFS warning (ubi0:0 pid 1683): ubifs_ro_mode [ubifs]:
switched to read-only mode, error -22
CPU: 2 PID: 1683 Comm: aa Not tainted 5.16.0-rc5-00184-g0bca5994cacc-dirty #308
Call Trace:
dump_stack+0x13/0x1b
ubifs_ro_mode+0x54/0x60 [ubifs]
ubifs_assert_failed+0x4b/0x80 [ubifs]
ubifs_releasepage+0x67/0x1d0 [ubifs]
try_to_release_page+0x57/0xe0
invalidate_inode_page+0xfb/0x130
__invalidate_mapping_pages+0xb9/0x280
invalidate_mapping_pagevec+0x12/0x20
generic_fadvise+0x303/0x3c0
ksys_fadvise64_64+0x4c/0xb0
[1] https://bugzilla.kernel.org/show_bug.cgi?id=215373
[2] https://linux-mtd.infradead.narkive.com/NQoBeT1u/patch-rfc-ubifs-fix-assert-failed-in-ubifs-set-page-dirty
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