In the Linux kernel, the following vulnerability has been resolved:
apparmor: fix out-of-bounds write when null terminating a label vec
aa_vec_unique() null terminates at vec[n - dups] when VEC_FLAG_TERMINATE
is passed. If the components are all distinct no duplicates are dropped,
dups is 0 and the terminator goes to vec[n], so the caller has to provide
room for n + 1 entries.
aa_label_strn_parse() sets up its vector with vec_setup(profile, vec, len,
gfp) and then calls aa_vec_unique(vec, len, VEC_FLAG_TERMINATE), but
vec_setup() does not reserve the terminator entry. Up to LOCAL_VEC_ENTRIES
it uses the local array of LOCAL_VEC_ENTRIES pointers, above that it
allocates exactly len pointers. The terminator therefore lands one entry
past the end of the local array when len is LOCAL_VEC_ENTRIES, and one
entry past the end of the allocation when len is larger.
len comes from the number of "//&" separated components in the label name
and label_count_strn_entries() does not bound it. An unprivileged task
reaches the parse by writing to /proc/self/attr/apparmor/current or through
lsm_set_self_attr(2), both of which go through do_setattr(), and the name
is parsed before the change_profile permission is checked.
The query_label() path behind the securityfs .access file, which is
mode 0666, performs no permission check at all. Every component has to
resolve to a loaded profile, so a system with policy loaded is required.
The other two VEC_FLAG_TERMINATE users work on a label vec that
aa_label_alloc() has already sized with "+ 1 for null terminator entry on
vec". Reserve the same entry in vec_setup() and DEFINE_VEC(). Passing
len + 1 from the caller instead would move len == LOCAL_VEC_ENTRIES out of
the local array and into kzalloc().
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.
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