| CVE |
Vendors |
Products |
Updated |
CVSS v3.1 |
| An integer underflow was found in the popt library when formatting help text for option tables that exceed the terminal width. A local user who can cause an application to print help under those conditions may cause that application to crash or fail to display help, resulting in a denial of service of the affected application. |
| The MCUmgr SMP-over-console transport decodes a base64 frame, reads a 16-bit packet length from it, verifies a CRC and then unconditionally strips the trailing CRC with rx_ctxt->nb->len -= 2U; in mcumgr_serial_process_frag() (subsys/mgmt/mcumgr/transport/src/serial_util.c). mcumgr_serial_extract_len() accepted any declared length, including 0 and 1, and a packet declaring length 0 passes the checksum test for free because crc16_itu_t() over zero bytes returns the zero seed. Since net_buf::len is a uint16_t, the subtraction underflows and the buffer is handed to SMP claiming roughly 65 KB of payload while its data area is only CONFIG_MCUMGR_TRANSPORT_NETBUF_SIZE bytes (default 384).
The trigger is a single unauthenticated 7-byte line on the management console — the 0x06 0x09 packet marker followed by the base64 group AAA= and a newline — delivered to any transport built on this helper: CONFIG_MCUMGR_TRANSPORT_UART (smp_uart.c) or CONFIG_MCUMGR_TRANSPORT_SHELL (smp_shell.c), both of which select MCUMGR_TRANSPORT_SERIAL_HAS_SMP_OVER_CONSOLE. No prior session state, fragmentation or credentials are required to trigger the underflow, and the malformed frame is mishandled before any command handler or command-level access control runs. The attacker only needs write access to that console, which on many boards is a USB CDC-ACM port rather than a bare UART header.
With the inflated length, smp_process_request_packet() in subsys/mgmt/mcumgr/smp/src/smp.c loses its bound: cbor_nb_reader_init() gives the CBOR decoder a ~65 KB window into a 384-byte buffer, and each request header's nh_len is checked only against the inflated length. On its own the 7-byte frame re-parses whatever stale bytes the reused pool buffer still holds, typically a replay of the previously received request followed by a parse error, without leaving the buffer. Because the transport is unauthenticated, though, the attacker also controls the frames sent before the trigger, and can stage buffer contents so that a request succeeds with an nh_len larger than the buffer; net_buf_pull(), guarded only by __ASSERT_NO_MSG, then moves the parse cursor out of bounds and the loop reads further headers and CBOR from adjacent memory. The consequence is an out-of-bounds read that can fault the MCUmgr thread (denial of service); memory disclosure is also possible, since the default-enabled os echo handler (CONFIG_MCUMGR_GRP_OS_ECHO) decodes its string inside that window and copies it into its response. There is no integrity gain beyond what the unauthenticated transport already permits.
The fix rejects any declared packet length of two bytes or fewer in mcumgr_serial_extract_len(), so the CRC-strip subtraction can no longer underflow. The identical pattern remains in the test-only loopback transport subsys/mgmt/mcumgr/transport/src/smp_dummy.c (CONFIG_MCUMGR_TRANSPORT_DUMMY), which has no external input path and therefore carries no practical exposure. |
| In the Linux kernel, the following vulnerability has been resolved:
net/sched: cake: reject overhead values that underflow length
CAKE accepts signed overhead values and stores them in an s16, but the
adjusted packet length calculation uses unsigned arithmetic. A negative
effective length can therefore wrap to a large value.
Such configurations make rate accounting depend on integer wraparound
rather than on the packet size userspace intended to model. A static
netlink lower bound is not enough because packets reaching CAKE can be
smaller than any reasonable manual-overhead allowance.
Fold the signed overhead adjustment into the existing datapath MPU clamp
so negative adjusted lengths are clamped before link-layer framing
adjustments. |
| In the Linux kernel, the following vulnerability has been resolved:
net: garp: fix unsigned integer underflow in garp_pdu_parse_attr
The receive-side GARP attribute parser computes dlen with reversed
operands:
dlen = sizeof(*ga) - ga->len;
ga->len is the on-wire attribute length and includes the GARP attribute
header. For normal attributes with data, ga->len is larger than
sizeof(*ga), so the subtraction underflows in unsigned arithmetic.
The resulting value is later passed to garp_attr_lookup(), whose length
argument is u8. After truncation, the parsed data length usually no
longer matches the length stored for locally registered attributes, so
received Join/Leave events are ignored. This breaks the GARP receive path
for common attributes, such as GVRP VLAN registration attributes.
Compute the data length as the attribute length minus the header length. |
| In the Linux kernel, the following vulnerability has been resolved:
thunderbolt: Reject zero-length property entries in validator
tb_property_entry_valid() accepts entries with length == 0 for
DIRECTORY, DATA, and TEXT types. A zero-length TEXT entry passes
validation but causes an underflow in the null-termination logic:
property->value.text[property->length * 4 - 1] = '\0';
When property->length is 0 this writes to offset -1 relative to
the allocation.
Reject zero-length entries early in the validator since they have no
valid representation in the XDomain property protocol. |
| In the Linux kernel, the following vulnerability has been resolved:
md/raid10: fix deadlock with check operation and nowait requests
When an array check is running it will raise the barrier at which point
normal requests will become blocked and increment the nr_pending value to
signal there is work pending inside of wait_barrier(). NOWAIT requests
do not block and so will return immediately with an error, and additionally
do not increment nr_pending in wait_barrier(). Upstream change commit
43806c3d5b9b ("raid10: cleanup memleak at raid10_make_request") added a
call to raid_end_bio_io() to fix a memory leak when NOWAIT requests hit
this condition. raid_end_bio_io() eventually calls allow_barrier() and
it will unconditionally do an atomic_dec_and_test(&conf->nr_pending) even
though the corresponding increment on nr_pending didn't happen in the
NOWAIT case.
This can be easily seen by starting a check operation while an application
is doing nowait IO on the same array. This results in a deadlocked state
due to nr_pending value underflowing and so the md resync thread gets stuck
waiting for nr_pending to == 0.
Output of r10conf state of the array when we hit this condition:
crash> struct r10conf
barrier = 1,
nr_pending = {
counter = -41
},
nr_waiting = 15,
nr_queued = 0,
Example of md_sync thread stuck waiting on raise_barrier() and other
requests stuck in wait_barrier():
md1_resync
[<0>] raise_barrier+0xce/0x1c0
[<0>] raid10_sync_request+0x1ca/0x1ed0
[<0>] md_do_sync+0x779/0x1110
[<0>] md_thread+0x90/0x160
[<0>] kthread+0xbe/0xf0
[<0>] ret_from_fork+0x34/0x50
[<0>] ret_from_fork_asm+0x1a/0x30
kworker/u1040:2+flush-253:4
[<0>] wait_barrier+0x1de/0x220
[<0>] regular_request_wait+0x30/0x180
[<0>] raid10_make_request+0x261/0x1000
[<0>] md_handle_request+0x13b/0x230
[<0>] __submit_bio+0x107/0x1f0
[<0>] submit_bio_noacct_nocheck+0x16f/0x390
[<0>] ext4_io_submit+0x24/0x40
[<0>] ext4_do_writepages+0x254/0xc80
[<0>] ext4_writepages+0x84/0x120
[<0>] do_writepages+0x7a/0x260
[<0>] __writeback_single_inode+0x3d/0x300
[<0>] writeback_sb_inodes+0x1dd/0x470
[<0>] __writeback_inodes_wb+0x4c/0xe0
[<0>] wb_writeback+0x18b/0x2d0
[<0>] wb_workfn+0x2a1/0x400
[<0>] process_one_work+0x149/0x330
[<0>] worker_thread+0x2d2/0x410
[<0>] kthread+0xbe/0xf0
[<0>] ret_from_fork+0x34/0x50
[<0>] ret_from_fork_asm+0x1a/0x30 |
| In the Linux kernel, the following vulnerability has been resolved:
fat: avoid parent link count underflow in rmdir
Corrupted FAT images can leave a directory inode with an incorrect
i_nlink (e.g. 2 even though subdirectories exist). rmdir then
unconditionally calls drop_nlink(dir) and can drive i_nlink to 0,
triggering the WARN_ON in drop_nlink().
Add a sanity check in vfat_rmdir() and msdos_rmdir(): only drop the
parent link count when it is at least 3, otherwise report a filesystem
error. |
| In the Linux kernel, the following vulnerability has been resolved:
btrfs: fix transaction abort on set received ioctl due to item overflow
If the set received ioctl fails due to an item overflow when attempting to
add the BTRFS_UUID_KEY_RECEIVED_SUBVOL we have to abort the transaction
since we did some metadata updates before.
This means that if a user calls this ioctl with the same received UUID
field for a lot of subvolumes, we will hit the overflow, trigger the
transaction abort and turn the filesystem into RO mode. A malicious user
could exploit this, and this ioctl does not even requires that a user
has admin privileges (CAP_SYS_ADMIN), only that he/she owns the subvolume.
Fix this by doing an early check for item overflow before starting a
transaction. This is also race safe because we are holding the subvol_sem
semaphore in exclusive (write) mode.
A test case for fstests will follow soon. |
| In the Linux kernel, the following vulnerability has been resolved:
EFI/CPER: don't dump the entire memory region
The current logic at cper_print_fw_err() doesn't check if the
error record length is big enough to handle offset. On a bad firmware,
if the ofset is above the actual record, length -= offset will
underflow, making it dump the entire memory.
The end result can be:
- the logic taking a lot of time dumping large regions of memory;
- data disclosure due to the memory dumps;
- an OOPS, if it tries to dump an unmapped memory region.
Fix it by checking if the section length is too small before doing
a hex dump.
[ rjw: Subject tweaks ] |
| An integer underflow vulnerability was found in MIT krb5 in the berval2tl_data() function in plugins/kdb/ldap/libkdb_ldap/ldap_principal2.c. The function performs an unsigned subtraction (bv_len - 2) without a prior bounds check. When bv_len is 0 or 1, the subtraction wraps to a large value which is then truncated to uint16_t, yielding 0xFFFE (65534) or 0xFFFF (65535). The subsequent malloc succeeds and memcpy reads up to 65534 bytes from a 0-1 byte buffer, resulting in a heap out-of-bounds read.
The attack vector involves a malicious or compromised LDAP KDB backend returning a krbExtraData attribute with bv_len < 2, triggering the underflow when the KDC or kadmind reads principal data. |
| In the Linux kernel, the following vulnerability has been resolved:
wifi: mac80211: Fix static_branch_dec() underflow for aql_disable.
syzbot reported static_branch_dec() underflow in aql_enable_write(). [0]
The problem is that aql_enable_write() does not serialise concurrent
write()s to the debugfs.
aql_enable_write() checks static_key_false(&aql_disable.key) and
later calls static_branch_inc() or static_branch_dec(), but the
state may change between the two calls.
aql_disable does not need to track inc/dec.
Let's use static_branch_enable() and static_branch_disable().
[0]:
val == 0
WARNING: kernel/jump_label.c:311 at __static_key_slow_dec_cpuslocked.part.0+0x107/0x120 kernel/jump_label.c:311, CPU#0: syz.1.3155/20288
Modules linked in:
CPU: 0 UID: 0 PID: 20288 Comm: syz.1.3155 Tainted: G U L syzkaller #0 PREEMPT(full)
Tainted: [U]=USER, [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
RIP: 0010:__static_key_slow_dec_cpuslocked.part.0+0x107/0x120 kernel/jump_label.c:311
Code: f2 c9 ff 5b 5d c3 cc cc cc cc e8 54 f2 c9 ff 48 89 df e8 ac f9 ff ff eb ad e8 45 f2 c9 ff 90 0f 0b 90 eb a2 e8 3a f2 c9 ff 90 <0f> 0b 90 eb 97 48 89 df e8 5c 4b 33 00 e9 36 ff ff ff 0f 1f 80 00
RSP: 0018:ffffc9000b9f7c10 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffffffff9b3e5d40 RCX: ffffffff823c57b4
RDX: ffff8880285a0000 RSI: ffffffff823c5846 RDI: ffff8880285a0000
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 000000000000000a
R13: 1ffff9200173ef88 R14: 0000000000000001 R15: ffffc9000b9f7e98
FS: 00007f530dd726c0(0000) GS:ffff8881245e3000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001140 CR3: 000000007cc4a000 CR4: 00000000003526f0
Call Trace:
<TASK>
__static_key_slow_dec_cpuslocked kernel/jump_label.c:297 [inline]
__static_key_slow_dec kernel/jump_label.c:321 [inline]
static_key_slow_dec+0x7c/0xc0 kernel/jump_label.c:336
aql_enable_write+0x2b2/0x310 net/mac80211/debugfs.c:343
short_proxy_write+0x133/0x1a0 fs/debugfs/file.c:383
vfs_write+0x2aa/0x1070 fs/read_write.c:684
ksys_pwrite64 fs/read_write.c:793 [inline]
__do_sys_pwrite64 fs/read_write.c:801 [inline]
__se_sys_pwrite64 fs/read_write.c:798 [inline]
__x64_sys_pwrite64+0x1eb/0x250 fs/read_write.c:798
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xc9/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f530cf9aeb9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f530dd72028 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007f530d215fa0 RCX: 00007f530cf9aeb9
RDX: 0000000000000003 RSI: 0000000000000000 RDI: 0000000000000010
RBP: 00007f530d008c1f R08: 0000000000000000 R09: 0000000000000000
R10: 4200000000000005 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f530d216038 R14: 00007f530d215fa0 R15: 00007ffde89fb978
</TASK> |
| P-Net before 1.0.3 contains an integer underflow in pf_cpm_c_data_ind(). When handling a received cyclic data frame while the consumer is in the FRUN or RUN state, the offset of the APDU status was computed as the frame length minus 4 using 16-bit arithmetic, without checking that the frame is long enough. A crafted short frame makes the offset wrap around, so the function reads outside the receive buffer. This can cause a crash (denial of service) or disclose memory content. |
| In the Linux kernel, the following vulnerability has been resolved:
watch_queue: fix pipe accounting mismatch
Currently, watch_queue_set_size() modifies the pipe buffers charged to
user->pipe_bufs without updating the pipe->nr_accounted on the pipe
itself, due to the if (!pipe_has_watch_queue()) test in
pipe_resize_ring(). This means that when the pipe is ultimately freed,
we decrement user->pipe_bufs by something other than what than we had
charged to it, potentially leading to an underflow. This in turn can
cause subsequent too_many_pipe_buffers_soft() tests to fail with -EPERM.
To remedy this, explicitly account for the pipe usage in
watch_queue_set_size() to match the number set via account_pipe_buffers()
(It's unclear why watch_queue_set_size() does not update nr_accounted;
it may be due to intentional overprovisioning in watch_queue_set_size()?) |
| In the Linux kernel, the following vulnerability has been resolved:
net: fix crash when config small gso_max_size/gso_ipv4_max_size
Config a small gso_max_size/gso_ipv4_max_size will lead to an underflow
in sk_dst_gso_max_size(), which may trigger a BUG_ON crash,
because sk->sk_gso_max_size would be much bigger than device limits.
Call Trace:
tcp_write_xmit
tso_segs = tcp_init_tso_segs(skb, mss_now);
tcp_set_skb_tso_segs
tcp_skb_pcount_set
// skb->len = 524288, mss_now = 8
// u16 tso_segs = 524288/8 = 65535 -> 0
tso_segs = DIV_ROUND_UP(skb->len, mss_now)
BUG_ON(!tso_segs)
Add check for the minimum value of gso_max_size and gso_ipv4_max_size. |
| A flaw was found in libsoup. An integer underflow vulnerability occurs when processing content with a zero-length resource, leading to a buffer overread. This can allow an attacker to potentially access sensitive information or cause an application level denial of service. |
| A flaw was found in open-iscsi. An integer underflow vulnerability in the `iscsiuio` component, specifically during IPv4 Dynamic Host Configuration Protocol (DHCP) parsing, allows a remote attacker on the same local network segment to cause a denial of service. By sending a specially crafted IPv4/UDP DHCP reply, the attacker can trigger an out-of-bounds read, leading to the `iscsiuio` process crashing. This issue affects systems where `iscsiuio` is actively handling IPv4 DHCP traffic. |
| A flaw was found in open-iscsi's iscsiuio component. This vulnerability involves an integer underflow and out-of-bounds read during Dynamic Host Configuration Protocol for IPv6 (DHCPv6) packet parsing. Specifically, crafted DHCPv6 Advertise traffic with a short User Datagram Protocol (UDP) length can cause the DHCPv6 payload length to underflow. An unauthenticated attacker on an adjacent network segment can exploit this by sending specially crafted IPv6 UDP traffic while the client is in an active DHCPv6 exchange, leading to a denial of service due to a process crash or service disruption. |
| An Integer Underflow vulnerability in DhcpMessageDecoder in Juniper Networks Session Smart Router allows an attacker with local network access to cause information disclosure and a denial of service via a malicious DHCP reply. |
| A flaw was found in 389 Directory Server. The SMD5 password storage plugin performs unsigned integer underflow when computing salt length from a crafted password hash shorter than 16 bytes, causing a buffer over-read that crashes the LDAP server during authentication. |
| Envoy is a cloud-native, open source edge and service proxy. There is a crash at `QuicheDataReader::PeekVarInt62Length()`. It is caused by integer underflow in the `QuicStreamSequencerBuffer::PeekRegion()` implementation. |
