In the Linux kernel, the following vulnerability has been resolved:
arm64: csum: Fix OoB access in IP checksum code for negative lengths
Although commit c2c24edb1d9c ("arm64: csum: Fix pathological zero-length
calls") added an early return for zero-length input, syzkaller has
popped up with an example of a _negative_ length which causes an
undefined shift and an out-of-bounds read:
| BUG: KASAN: slab-out-of-bounds in do_csum+0x44/0x254 arch/arm64/lib/csum.c:39
| Read of size 4294966928 at addr ffff0000d7ac0170 by task syz-executor412/5975
|
| CPU: 0 PID: 5975 Comm: syz-executor412 Not tainted 6.4.0-rc4-syzkaller-g908f31f2a05b #0
| Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
| Call trace:
| dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:233
| show_stack+0x2c/0x44 arch/arm64/kernel/stacktrace.c:240
| __dump_stack lib/dump_stack.c:88 [inline]
| dump_stack_lvl+0xd0/0x124 lib/dump_stack.c:106
| print_address_description mm/kasan/report.c:351 [inline]
| print_report+0x174/0x514 mm/kasan/report.c:462
| kasan_report+0xd4/0x130 mm/kasan/report.c:572
| kasan_check_range+0x264/0x2a4 mm/kasan/generic.c:187
| __kasan_check_read+0x20/0x30 mm/kasan/shadow.c:31
| do_csum+0x44/0x254 arch/arm64/lib/csum.c:39
| csum_partial+0x30/0x58 lib/checksum.c:128
| gso_make_checksum include/linux/skbuff.h:4928 [inline]
| __udp_gso_segment+0xaf4/0x1bc4 net/ipv4/udp_offload.c:332
| udp6_ufo_fragment+0x540/0xca0 net/ipv6/udp_offload.c:47
| ipv6_gso_segment+0x5cc/0x1760 net/ipv6/ip6_offload.c:119
| skb_mac_gso_segment+0x2b4/0x5b0 net/core/gro.c:141
| __skb_gso_segment+0x250/0x3d0 net/core/dev.c:3401
| skb_gso_segment include/linux/netdevice.h:4859 [inline]
| validate_xmit_skb+0x364/0xdbc net/core/dev.c:3659
| validate_xmit_skb_list+0x94/0x130 net/core/dev.c:3709
| sch_direct_xmit+0xe8/0x548 net/sched/sch_generic.c:327
| __dev_xmit_skb net/core/dev.c:3805 [inline]
| __dev_queue_xmit+0x147c/0x3318 net/core/dev.c:4210
| dev_queue_xmit include/linux/netdevice.h:3085 [inline]
| packet_xmit+0x6c/0x318 net/packet/af_packet.c:276
| packet_snd net/packet/af_packet.c:3081 [inline]
| packet_sendmsg+0x376c/0x4c98 net/packet/af_packet.c:3113
| sock_sendmsg_nosec net/socket.c:724 [inline]
| sock_sendmsg net/socket.c:747 [inline]
| __sys_sendto+0x3b4/0x538 net/socket.c:2144
Extend the early return to reject negative lengths as well, aligning our
implementation with the generic code in lib/checksum.c
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (7.1): severity, escalated by confirmed exploitation. This CVE's 7.1 is its impact severity (EG Severity), not escalated.
- EG Severity
- 7.1 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.1% 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 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