In the Linux kernel, the following vulnerability has been resolved:
udf: Avoid double brelse() in udf_rename()
syzbot reported a warning like below [1]:
VFS: brelse: Trying to free free buffer
WARNING: CPU: 2 PID: 7301 at fs/buffer.c:1145 __brelse+0x67/0xa0
...
Call Trace:
invalidate_bh_lru+0x99/0x150
smp_call_function_many_cond+0xe2a/0x10c0
? generic_remap_file_range_prep+0x50/0x50
? __brelse+0xa0/0xa0
? __mutex_lock+0x21c/0x12d0
? smp_call_on_cpu+0x250/0x250
? rcu_read_lock_sched_held+0xb/0x60
? lock_release+0x587/0x810
? __brelse+0xa0/0xa0
? generic_remap_file_range_prep+0x50/0x50
on_each_cpu_cond_mask+0x3c/0x80
blkdev_flush_mapping+0x13a/0x2f0
blkdev_put_whole+0xd3/0xf0
blkdev_put+0x222/0x760
deactivate_locked_super+0x96/0x160
deactivate_super+0xda/0x100
cleanup_mnt+0x222/0x3d0
task_work_run+0x149/0x240
? task_work_cancel+0x30/0x30
do_exit+0xb29/0x2a40
? reacquire_held_locks+0x4a0/0x4a0
? do_raw_spin_lock+0x12a/0x2b0
? mm_update_next_owner+0x7c0/0x7c0
? rwlock_bug.part.0+0x90/0x90
? zap_other_threads+0x234/0x2d0
do_group_exit+0xd0/0x2a0
__x64_sys_exit_group+0x3a/0x50
do_syscall_64+0x34/0xb0
entry_SYSCALL_64_after_hwframe+0x63/0xcd
The cause of the issue is that brelse() is called on both ofibh.sbh
and ofibh.ebh by udf_find_entry() when it returns NULL. However,
brelse() is called by udf_rename(), too. So, b_count on buffer_head
becomes unbalanced.
This patch fixes the issue by not calling brelse() by udf_rename()
when udf_find_entry() returns NULL.
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 2026-10-30). 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 (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (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 Vulnrichment) · Technical impact total (CISA Vulnrichment). 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