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NVD / CVE Program· CNA Linux

CVE-2026-64540: usbnet: gl620a: fix out-of-bounds read in genelink_rx_fixup()

Noroxi assessment

Priority: Monitor (action score 32/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.27% (FIRST EPSS).
  • Someone on the same network segment can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 0575599e451aff3c5329922562374a2cab25fc51, 0a7d9c7c5f1f208c523abbb4db6aea7bc1fad3db, 255d03551f94c7bdd86c7d9181a70b21917d829f.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 0575599e451aff3c5329922562374a2cab25fc51, 0a7d9c7c5f1f208c523abbb4db6aea7bc1fad3db, 255d03551f94c7bdd86c7d9181a70b21917d829f or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

HighCVSS 8.1 · v3.1—No exploit Fix available
Published
Jul 27, 2026
Updated
Nov 3, 2026
EPSS
0.2% · 20th percentile

Report tools

JSON

Action score

32

Monitor

Low priority for now.

CVSS
32 / 40 · 8.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
8.1
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 2.6.14affected
    • 47ee3051c856cc2aa95d35d577a8cb37279d540f and later · before 255d03551f94c7bdd86c7d9181a70b21917d829faffected · git
    • 47ee3051c856cc2aa95d35d577a8cb37279d540f and later · before 4359376e6238d89977a35086e47ca3b07f43e850affected · git
    • 47ee3051c856cc2aa95d35d577a8cb37279d540f and later · before 8624e179fa3ce23c2fbd1a198ce30764b73f054aaffected · git
    • 47ee3051c856cc2aa95d35d577a8cb37279d540f and later · before 573418f7ea8f859a841417eb4b915594094fd967affected · git
    • 47ee3051c856cc2aa95d35d577a8cb37279d540f and later · before 0575599e451aff3c5329922562374a2cab25fc51affected · git
    • 47ee3051c856cc2aa95d35d577a8cb37279d540f and later · before 0a7d9c7c5f1f208c523abbb4db6aea7bc1fad3dbaffected · git
    • 47ee3051c856cc2aa95d35d577a8cb37279d540f and later · before 3ef79fa3860e644c8de7834fa7300e1c58f38862affected · git
    • 47ee3051c856cc2aa95d35d577a8cb37279d540f and later · before 8ff7f2a6da4fccaa5cc9be7251a24e71e29fbd1aaffected · git
    • before 2.6.14not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.180-16.1.180-1
Debian:12linux-6.12before 6.12.100-1~deb12u16.12.100-1~deb12u1
Debian:13linuxbefore 6.12.100-16.12.100-1
Debian:14linuxbefore 7.1.5-17.1.5-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-64538Jul 27, 2026 · ipv6: Fix null-ptr-deref in fib6_nh_mtu_change().
    0Monitor
  • ← EarlierCVE-2026-64539Jul 27, 2026 · Bluetooth: eir: Fix stack OOB write when prepending the Flags AD
    31Monitor
  • Later →CVE-2026-64541Jul 27, 2026 · net/smc: fix UAF in smc_cdc_rx_handler() by pinning the socket
    39Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux0575599e451aff3c5329922562374a2cab25fc51Vendor (CNA)
Linux Linux0a7d9c7c5f1f208c523abbb4db6aea7bc1fad3dbVendor (CNA)
Linux Linux255d03551f94c7bdd86c7d9181a70b21917d829fVendor (CNA)
Linux Linux3ef79fa3860e644c8de7834fa7300e1c58f38862Vendor (CNA)
Linux Linux4359376e6238d89977a35086e47ca3b07f43e850Vendor (CNA)
Linux Linux573418f7ea8f859a841417eb4b915594094fd967Vendor (CNA)
Linux Linux8624e179fa3ce23c2fbd1a198ce30764b73f054aVendor (CNA)
Linux Linux8ff7f2a6da4fccaa5cc9be7251a24e71e29fbd1aVendor (CNA)
debian:linux6.1.180-1 · Debian:12Package registry (OSV)
debian:linux-6.126.12.100-1~deb12u1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-6808212 days apartlibceph: fix two unsafe bare decodes in decode_lockers()
    39Monitor
  • CVE-2026-6816014 days apartceph: fix pre-auth out-of-bounds read on snaptrace in ceph_handle_caps()
    39Monitor
  • CVE-2026-6838814 days apartsmb/client: handle overlapping allocated ranges in fallocate
    39Monitor
  • CVE-2026-7208419 days apartscsi: target: Bound PR-OUT TransportID parsing to the received buffer
    39Monitor
  • CVE-2026-645510 days apartsctp: validate STALE_COOKIE cause length before reading staleness
    36Monitor
  • CVE-2026-6834314 days apartsmb: client: validate DFS referral PathConsumed
    36Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Someone on the same network segment can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Adjacent
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-125 · Out-of-bounds Read

CVSS vector

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records