Summary
In the Linux kernel, the following vulnerability has been resolved: arm64: csum: Fix OoB access...
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
Impact
CVE-2023-53726 has a CVSS score of 7.1 (High). The vector is requires local access, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
Frequently Asked Questions
- What is CVE-2023-53726? CVE-2023-53726 is a high-severity security vulnerability. No fixed version is listed yet.
- How severe is CVE-2023-53726? CVE-2023-53726 has a CVSS score of 7.1 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Is there a fix for CVE-2023-53726? No fixed version is listed for CVE-2023-53726 yet. Monitor the advisory for updates and apply mitigations in the interim.
- Is CVE-2023-53726 exploitable, and should I be worried? Whether CVE-2023-53726 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2023-53726 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.