Summary
In the Linux kernel, the following vulnerability has been resolved: usbnet: gl620a: fix endpoint...
In the Linux kernel, the following vulnerability has been resolved:
usbnet: gl620a: fix endpoint checking in genelink_bind()
Syzbot reports [1] a warning in usb_submit_urb() triggered by
inconsistencies between expected and actually present endpoints
in gl620a driver. Since genelink_bind() does not properly
verify whether specified eps are in fact provided by the device,
in this case, an artificially manufactured one, one may get a
mismatch.
Fix the issue by resorting to a usbnet utility function
usbnet_get_endpoints(), usually reserved for this very problem.
Check for endpoints and return early before proceeding further if
any are missing.
[1] Syzbot report:
usb 5-1: Manufacturer: syz
usb 5-1: SerialNumber: syz
usb 5-1: config 0 descriptor??
gl620a 5-1:0.23 usb0: register 'gl620a' at usb-dummy_hcd.0-1, ...
------------[ cut here ]------------
usb 5-1: BOGUS urb xfer, pipe 3 != type 1
WARNING: CPU: 2 PID: 1841 at drivers/usb/core/urb.c:503 usb_submit_urb+0xe4b/0x1730 drivers/usb/core/urb.c:503
Modules linked in:
CPU: 2 UID: 0 PID: 1841 Comm: kworker/2:2 Not tainted 6.12.0-syzkaller-07834-g06afb0f36106 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: mld mld_ifc_work
RIP: 0010:usb_submit_urb+0xe4b/0x1730 drivers/usb/core/urb.c:503
...
Call Trace:
usbnet_start_xmit+0x6be/0x2780 drivers/net/usb/usbnet.c:1467
__netdev_start_xmit include/linux/netdevice.h:5002 [inline]
netdev_start_xmit include/linux/netdevice.h:5011 [inline]
xmit_one net/core/dev.c:3590 [inline]
dev_hard_start_xmit+0x9a/0x7b0 net/core/dev.c:3606
sch_direct_xmit+0x1ae/0xc30 net/sched/sch_generic.c:343
__dev_xmit_skb net/core/dev.c:3827 [inline]
__dev_queue_xmit+0x13d4/0x43e0 net/core/dev.c:4400
dev_queue_xmit include/linux/netdevice.h:3168 [inline]
neigh_resolve_output net/core/neighbour.c:1514 [inline]
neigh_resolve_output+0x5bc/0x950 net/core/neighbour.c:1494
neigh_output include/net/neighbour.h:539 [inline]
ip6_finish_output2+0xb1b/0x2070 net/ipv6/ip6_output.c:141
__ip6_finish_output net/ipv6/ip6_output.c:215 [inline]
ip6_finish_output+0x3f9/0x1360 net/ipv6/ip6_output.c:226
NF_HOOK_COND include/linux/netfilter.h:303 [inline]
ip6_output+0x1f8/0x540 net/ipv6/ip6_output.c:247
dst_output include/net/dst.h:450 [inline]
NF_HOOK include/linux/netfilter.h:314 [inline]
NF_HOOK include/linux/netfilter.h:308 [inline]
mld_sendpack+0x9f0/0x11d0 net/ipv6/mcast.c:1819
mld_send_cr net/ipv6/mcast.c:2120 [inline]
mld_ifc_work+0x740/0xca0 net/ipv6/mcast.c:2651
process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3229
process_scheduled_works kernel/workqueue.c:3310 [inline]
worker_thread+0x6c8/0xf00 kernel/workqueue.c:3391
kthread+0x2c1/0x3a0 kernel/kthread.c:389
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
Impact
CVE-2025-21877 has a CVSS score of 5.5 (Medium). 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.
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Frequently Asked Questions
- What is CVE-2025-21877? CVE-2025-21877 is a medium-severity security vulnerability. No fixed version is listed yet.
- How severe is CVE-2025-21877? CVE-2025-21877 has a CVSS score of 5.5 (Medium). 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-2025-21877? No fixed version is listed for CVE-2025-21877 yet. Monitor the advisory for updates and apply mitigations in the interim.
- Is CVE-2025-21877 exploitable, and should I be worried? Whether CVE-2025-21877 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-2025-21877 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.