In the Linux kernel, the following vulnerability has been resolved:
macsec: fix UAF bug for real_dev
Create a new macsec device but not get reference to real_dev. That can
not ensure that real_dev is freed after macsec. That will trigger the
UAF bug for real_dev as following:
==================================================================
BUG: KASAN: use-after-free in macsec_get_iflink+0x5f/0x70 drivers/net/macsec.c:3662
Call Trace:
...
macsec_get_iflink+0x5f/0x70 drivers/net/macsec.c:3662
dev_get_iflink+0x73/0xe0 net/core/dev.c:637
default_operstate net/core/link_watch.c:42 [inline]
rfc2863_policy+0x233/0x2d0 net/core/link_watch.c:54
linkwatch_do_dev+0x2a/0x150 net/core/link_watch.c:161
Allocated by task 22209:
...
alloc_netdev_mqs+0x98/0x1100 net/core/dev.c:10549
rtnl_create_link+0x9d7/0xc00 net/core/rtnetlink.c:3235
veth_newlink+0x20e/0xa90 drivers/net/veth.c:1748
Freed by task 8:
...
kfree+0xd6/0x4d0 mm/slub.c:4552
kvfree+0x42/0x50 mm/util.c:615
device_release+0x9f/0x240 drivers/base/core.c:2229
kobject_cleanup lib/kobject.c:673 [inline]
kobject_release lib/kobject.c:704 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x1c8/0x540 lib/kobject.c:721
netdev_run_todo+0x72e/0x10b0 net/core/dev.c:10327
After commit faab39f63c1f ("net: allow out-of-order netdev unregistration")
and commit e5f80fcf869a ("ipv6: give an IPv6 dev to blackhole_netdev"), we
can add dev_hold_track() in macsec_dev_init() and dev_put_track() in
macsec_free_netdev() to fix the problem.
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
- 0.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-28). 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