In the Linux kernel, the following vulnerability has been resolved:
drm/ttm: fix undefined behavior in bit shift for TTM_TT_FLAG_PRIV_POPULATED
Shifting signed 32-bit value by 31 bits is undefined, so changing
significant bit to unsigned. The UBSAN warning calltrace like below:
UBSAN: shift-out-of-bounds in ./include/drm/ttm/ttm_tt.h:122:26
left shift of 1 by 31 places cannot be represented in type 'int'
Call Trace:
dump_stack_lvl+0x7d/0xa5
dump_stack+0x15/0x1b
ubsan_epilogue+0xe/0x4e
__ubsan_handle_shift_out_of_bounds+0x1e7/0x20c
ttm_bo_move_memcpy+0x3b4/0x460 [ttm]
bo_driver_move+0x32/0x40 [drm_vram_helper]
ttm_bo_handle_move_mem+0x118/0x200 [ttm]
ttm_bo_validate+0xfa/0x220 [ttm]
drm_gem_vram_pin_locked+0x70/0x1b0 [drm_vram_helper]
drm_gem_vram_pin+0x48/0xb0 [drm_vram_helper]
drm_gem_vram_plane_helper_prepare_fb+0x53/0xe0 [drm_vram_helper]
drm_gem_vram_simple_display_pipe_prepare_fb+0x26/0x30 [drm_vram_helper]
drm_simple_kms_plane_prepare_fb+0x4d/0xe0 [drm_kms_helper]
drm_atomic_helper_prepare_planes+0xda/0x210 [drm_kms_helper]
drm_atomic_helper_commit+0xc3/0x1e0 [drm_kms_helper]
drm_atomic_commit+0x9c/0x160 [drm]
drm_client_modeset_commit_atomic+0x33a/0x380 [drm]
drm_client_modeset_commit_locked+0x77/0x220 [drm]
drm_client_modeset_commit+0x31/0x60 [drm]
__drm_fb_helper_restore_fbdev_mode_unlocked+0xa7/0x170 [drm_kms_helper]
drm_fb_helper_set_par+0x51/0x90 [drm_kms_helper]
fbcon_init+0x316/0x790
visual_init+0x113/0x1d0
do_bind_con_driver+0x2a3/0x5c0
do_take_over_console+0xa9/0x270
do_fbcon_takeover+0xa1/0x170
do_fb_registered+0x2a8/0x340
fbcon_fb_registered+0x47/0xe0
register_framebuffer+0x294/0x4a0
__drm_fb_helper_initial_config_and_unlock+0x43c/0x880 [drm_kms_helper]
drm_fb_helper_initial_config+0x52/0x80 [drm_kms_helper]
drm_fbdev_client_hotplug+0x156/0x1b0 [drm_kms_helper]
drm_fbdev_generic_setup+0xfc/0x290 [drm_kms_helper]
bochs_pci_probe+0x6ca/0x772 [bochs]
local_pci_probe+0x4d/0xb0
pci_device_probe+0x119/0x320
really_probe+0x181/0x550
__driver_probe_device+0xc6/0x220
driver_probe_device+0x32/0x100
__driver_attach+0x195/0x200
bus_for_each_dev+0xbb/0x120
driver_attach+0x27/0x30
bus_add_driver+0x22e/0x2f0
driver_register+0xa9/0x190
__pci_register_driver+0x90/0xa0
bochs_pci_driver_init+0x52/0x1000 [bochs]
do_one_initcall+0x76/0x430
do_init_module+0x61/0x28a
load_module+0x1f82/0x2e50
__do_sys_finit_module+0xf8/0x190
__x64_sys_finit_module+0x23/0x30
do_syscall_64+0x58/0x80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
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 every mission impact level.CISA BOD 26-04: 60 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 every mission impact level.
A fix is available. Apply it within your standard update timelines.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (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)60 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 partial (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