Linux: >> Linux Kernel >> 5.10.171 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
net: sched: cls_api: fix tc_chain_fill_node to initialize tcm_info to zero to prevent an info-leak
When building netlink messages, tc_chain_fill_node() never initializes
the tcm_info field of struct tcmsg. Since the allocation is not zeroed,
kernel heap memory is leaked to userspace through this 4-byte field.
The fix simply zeroes tcm_info alongside the other fields that are
already initialized.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
net: use skb_header_pointer() for TCPv4 GSO frag_off check
Syzbot reported a KMSAN uninit-value warning in gso_features_check()
called from netif_skb_features() [1].
gso_features_check() reads iph->frag_off to decide whether to clear
mangleid_features. Accessing the IPv4 header via ip_hdr()/inner_ip_hdr()
can rely on skb header offsets that are not always safe for direct
dereference on packets injected from PF_PACKET paths.
Use skb_header_pointer() for the TCPv4 frag_off check so the header read
is robust whether data is already linear or needs copying.
[1] https://syzkaller.appspot.com/bug?extid=1543a7d954d9c6d00407
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
ip6_tunnel: clear skb2->cb[] in ip4ip6_err()
Oskar Kjos reported the following problem.
ip4ip6_err() calls icmp_send() on a cloned skb whose cb[] was written
by the IPv6 receive path as struct inet6_skb_parm. icmp_send() passes
IPCB(skb2) to __ip_options_echo(), which interprets that cb[] region
as struct inet_skb_parm (IPv4). The layouts differ: inet6_skb_parm.nhoff
at offset 14 overlaps inet_skb_parm.opt.rr, producing a non-zero rr
value. __ip_options_echo() then reads optlen from attacker-controlled
packet data at sptr[rr+1] and copies that many bytes into dopt->__data,
a fixed 40-byte stack buffer (IP_OPTIONS_DATA_FIXED_SIZE).
To fix this we clear skb2->cb[], as suggested by Oskar Kjos.
Also add minimal IPv4 header validation (version == 4, ihl >= 5).
CVSS Score
9.8
EPSS Score
0.005
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach()
Sashiko AI-review observed:
In ip6_err_gen_icmpv6_unreach(), the skb is an outer IPv4 ICMP error packet
where its cb contains an IPv4 inet_skb_parm. When skb is cloned into skb2
and passed to icmp6_send(), it uses IP6CB(skb2).
IP6CB interprets the IPv4 inet_skb_parm as an inet6_skb_parm. The cipso
offset in inet_skb_parm.opt directly overlaps with dsthao in inet6_skb_parm
at offset 18.
If an attacker sends a forged ICMPv4 error with a CIPSO IP option, dsthao
would be a non-zero offset. Inside icmp6_send(), mip6_addr_swap() is called
and uses ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO).
This would scan the inner, attacker-controlled IPv6 packet starting at that
offset, potentially returning a fake TLV without checking if the remaining
packet length can hold the full 18-byte struct ipv6_destopt_hao.
Could mip6_addr_swap() then perform a 16-byte swap that extends past the end
of the packet data into skb_shared_info?
Should the cb array also be cleared in ip6_err_gen_icmpv6_unreach() and
ip6ip6_err() to prevent this?
This patch implements the first suggestion.
I am not sure if ip6ip6_err() needs to be changed.
A separate patch would be better anyway.
CVSS Score
9.8
EPSS Score
0.004
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
netfilter: ctnetlink: zero expect NAT fields when CTA_EXPECT_NAT absent
ctnetlink_alloc_expect() allocates expectations from a non-zeroing
slab cache via nf_ct_expect_alloc(). When CTA_EXPECT_NAT is not
present in the netlink message, saved_addr and saved_proto are
never initialized. Stale data from a previous slab occupant can
then be dumped to userspace by ctnetlink_exp_dump_expect(), which
checks these fields to decide whether to emit CTA_EXPECT_NAT.
The safe sibling nf_ct_expect_init(), used by the packet path,
explicitly zeroes these fields.
Zero saved_addr, saved_proto and dir in the else branch, guarded
by IS_ENABLED(CONFIG_NF_NAT) since these fields only exist when
NAT is enabled.
Confirmed by priming the expect slab with NAT-bearing expectations,
freeing them, creating a new expectation without CTA_EXPECT_NAT,
and observing that the ctnetlink dump emits a spurious
CTA_EXPECT_NAT containing stale data from the prior allocation.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_conntrack_helper: pass helper to expect cleanup
nf_conntrack_helper_unregister() calls nf_ct_expect_iterate_destroy()
to remove expectations belonging to the helper being unregistered.
However, it passes NULL instead of the helper pointer as the data
argument, so expect_iter_me() never matches any expectation and all
of them survive the cleanup.
After unregister returns, nfnl_cthelper_del() frees the helper
object immediately. Subsequent expectation dumps or packet-driven
init_conntrack() calls then dereference the freed exp->helper,
causing a use-after-free.
Pass the actual helper pointer so expectations referencing it are
properly destroyed before the helper object is freed.
BUG: KASAN: slab-use-after-free in string+0x38f/0x430
Read of size 1 at addr ffff888003b14d20 by task poc/103
Call Trace:
string+0x38f/0x430
vsnprintf+0x3cc/0x1170
seq_printf+0x17a/0x240
exp_seq_show+0x2e5/0x560
seq_read_iter+0x419/0x1280
proc_reg_read+0x1ac/0x270
vfs_read+0x179/0x930
ksys_read+0xef/0x1c0
Freed by task 103:
The buggy address is located 32 bytes inside of
freed 192-byte region [ffff888003b14d00, ffff888003b14dc0)
CVSS Score
7.8
EPSS Score
0.001
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
netfilter: x_tables: ensure names are nul-terminated
Reject names that lack a \0 character before feeding them
to functions that expect c-strings.
Fixes tag is the most recent commit that needs this change.
CVSS Score
7.1
EPSS Score
0.001
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix regsafe() for pointers to packet
In case rold->reg->range == BEYOND_PKT_END && rcur->reg->range == N
regsafe() may return true which may lead to current state with
valid packet range not being explored. Fix the bug.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
NFC: pn533: bound the UART receive buffer
pn532_receive_buf() appends every incoming byte to dev->recv_skb and
only resets the buffer after pn532_uart_rx_is_frame() recognizes a
complete frame. A continuous stream of bytes without a valid PN532 frame
header therefore keeps growing the skb until skb_put_u8() hits the tail
limit.
Drop the accumulated partial frame once the fixed receive buffer is full
so malformed UART traffic cannot grow the skb past
PN532_UART_SKB_BUFF_LEN.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
crypto: authencesn - Do not place hiseq at end of dst for out-of-place decryption
When decrypting data that is not in-place (src != dst), there is
no need to save the high-order sequence bits in dst as it could
simply be re-copied from the source.
However, the data to be hashed need to be rearranged accordingly.
Thanks,
CVSS Score
7.8
EPSS Score
0.001
Published
2026-05-01