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CVE-2026-64540

Canonical Ubuntu Linux: out-of-bounds read can lead to information disclosure

Risk score
64/100
CVSS
8.1 v3.1
Published
27 Jul 2026

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What to know

What it is
In the Linux kernel, the following vulnerability has been resolved: usbnet: gl620a: fix out-of-bounds read in genelink_rx_fixup() genelink_rx_fixup() splits an aggregated RX frame into its individual packets, using a per-packet length taken from device-supplied data. That length is only bounded by GL_MAX_PACKET_LEN (1…
Affected
Canonical Ubuntu Linux
Fix
Apply the vendor's security update; see the linked advisory.
Exploitation
No known exploitation

Story map

Story map: Canonical Ubuntu LinuxTHE FLAWSTHE FIXCVE-2026-64540Out-of-bounds read can lead toinformation disclosureCVSS 8.1CVE-2026-93479Heap buffer overflow can leadto remote code executionCVSS 8.1 · EPSS 1%CVE-2026-15176Heap buffer overflow can leadto remote code executionCVSS 8.1 · EPSS 1%CVE-2026-97205NGINX Plus and NGINX OpenSource have a vulnerability inthe ngx_http_core_module…CVSS 8.1 · EPSS 1%FixCheck the linked advisory forthe concrete fix.Who is exposed{'products': ['NGINX Plus','NGINX Open Source'],'packages': [], 'versions': []}RED · ACT TODAYCanonical UbuntuLinuxA vulnerability exists in NGINXPlus and NGINX Open Sourcewhen a map directive uses regexmatching and the root directiveor access log format referencesthe map's regex capturevariables before referencing…Where it standsNo known exploitationHOW IT UNFOLDEDOfficial record on the left, the press on the right, oldest first.26 Oct · Ubuntu security noticesUSN-8955-1: nginx vulnerabilities5 Nov · Ubuntu security noticesUSN-8955-2: nginx vulnerabilities6 Nov · Ubuntu security noticesUSN-9003-1: Linux kernel (NVIDIA) vulnerabilitiesCONNECTS TOSame weaknessOut-of-bounds read (CWE-125)399 other warnings in 30 days →Same productEarlier Canonical Ubuntu Linux warnings163 in the last 90 days →
Story map: the flaws, the fix, how it unfolded and what it connects to. Boxes link to the record or article.

At a glance

Canonical Ubuntu Linux: Red, act today. A vulnerability exists in NGINX Plus and NGINX Open Source when a map directive uses regex matching and the root directive or access log format references the map's regex capture variables before referencing the map output variable. An unauthenticated attacker can exploit this vulnerability by sending crafted HTTP requests, causing a heap buffer overflow in the NGINX worker process leading to a restart, or potential…

The flaws

  • CVE-2026-64540: Out-of-bounds read can lead to information disclosure (CVSS 8.1)
  • CVE-2026-93479: Heap buffer overflow can lead to remote code execution (CVSS 8.1 · EPSS 1%)
  • CVE-2026-15176: Heap buffer overflow can lead to remote code execution (CVSS 8.1 · EPSS 1%)
  • CVE-2026-97205: NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_core_module module (CVSS 8.1 · EPSS 1%)

The fix

Fix: Check the linked advisory for the concrete fix.

Who is exposed: {'products': ['NGINX Plus', 'NGINX Open Source'], 'packages': [], 'versions': []}

Where it stands

  • No known exploitation

How it unfolded

  1. 26 Oct, Ubuntu security notices (official): USN-8955-1: nginx vulnerabilities
  2. 5 Nov, Ubuntu security notices (official): USN-8955-2: nginx vulnerabilities
  3. 6 Nov, Ubuntu security notices (official): USN-9003-1: Linux kernel (NVIDIA) vulnerabilities

Connects to

Why it is Amber

  • CVSS 8.1 high
  • On your watchlist: linux kernel
  • Named in a government or vendor bulletin

Government and vendor bulletins

References

Original description

In the Linux kernel, the following vulnerability has been resolved: usbnet: gl620a: fix out-of-bounds read in genelink_rx_fixup() genelink_rx_fixup() splits an aggregated RX frame into its individual packets, using a per-packet length taken from device-supplied data. That length is only bounded by GL_MAX_PACKET_LEN (1514); it is never compared against how many bytes were actually received. A malicious GeneLink (GL620A) device can therefore send a short URB whose header claims packet_count > 1 and a first packet of up to 1514 bytes. skb_put_data(gl_skb, packet->packet_data, size); then copies past the end of the receive buffer and hands the adjacent slab contents up the network stack, an out-of-bounds read that leaks kernel heap. No privilege is required: the path runs in the usbnet RX softirq as soon as the interface is up. BUG: KASAN: slab-out-of-bounds in genelink_rx_fixup (drivers/net/usb/gl620a.c:112) Read of size 1514 at addr ffff888011309708 by task ksoftirqd/0/14 Call Trace: ... __asan_memcpy (mm/kasan/shadow.c:105) genelink_rx_fixup (include/linux/skbuff.h:2814 drivers/net/usb/gl620a.c:112) usbnet_bh (drivers/net/usb/usbnet.c:572 drivers/net/usb/usbnet.c:1589) process_one_work (kernel/workqueue.c:3322) bh_worker (kernel/workqueue.c:3405) tasklet_action (kernel/softirq.c:965) handle_softirqs (kernel/softirq.c:622) run_ksoftirqd (kernel/softirq.c:1076) ... skb_pull() already verifies that the requested length fits the buffer and returns NULL otherwise. Move it ahead of the copy and check its result, so a packet that overruns the received data is rejected before it is read. Well-formed frames, whose packets are fully present, are unaffected.

Last activity 6 Nov 2026. Patch Forecast updates every hour.