CVE-2026-52940

mediumpriority · track · 22EPSS 0.002 · 5 %ileDEEURUUS
grimoire priorityP3 · Track
Exploitable?
—
no known exploitation
Likely / severe?
0.16% (5th) EPSS
CVSS 5.5 · medium
Is it mine?
30 products
Check your exposure
Who says so?
4 sources
cnnvd · enisa_euvd · fstec_bdu · cert_bund

EPSS · scored 2026-10-27

In the Linux kernel, the following vulnerability has been resolved: tun: zero the whole vnet header in tun_put_user() tun_put_user() declares an on-stack struct virtio_net_hdr_v1_hash_tunnel without zeroing it. For a non-tunnel skb, virtio_net_hdr_tnl_from_skb() only initializes the first 10 bytes (sizeof(struct virtio_net_hdr)), leaving bytes 10..23 (num_buffers and the hash/tunnel fields) as stack garbage. An unprivileged user can set the vnet header size to 24 with TUNSETVNETHDRSZ, so __tun_vnet_hdr_put() copies all 24 bytes of the partially-initialized struct to userspace, leaking 14 bytes of kernel stack on every read of a non-tunnel packet. Fix it the same way tun_get_user() already does by zeroing the whole header right after declaration.

01

cvss

Technical severity, 0–10. One row per scoring source.

7.0
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 5.1–7

v3.15.5mediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:Hprimary · NVD / NIST USexploitability 1.8 · impact 3.6
v3.17highAV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:Hsecondary · FSTEC (BDU) RU
v3.15.1mediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:Usecondary · CVSS-BT (t0sche)
02

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-200USCWE-909US
03

affected products (30)

Products and version ranges known to be affected.

showing 20 of 30
04

advisories (1)

Vendor and ecosystem advisories describing this.

  • WID-SEC-W-2026-2056Linux Kernel: Mehrere SchwachstellenDeutsch2026-06-23csaf · cert_bundDE

    Ein Angreifer kann mehrere Schwachstellen im Linux Kernel ausnutzen, um einen Denial-of-Service-Angriff auszulösen oder andere, nicht näher spezifizierte Angriffe durchzuführen.

05

also known as (4)

Other names and identifiers for this entity.

06

sources

Which sources assert this record, and when.

cnnvdenisa_euvdfstec_bducert_bundNVDCVE.orgMITRE
published 2026-06-24modified 2026-09-04
07

references (10)

External citations — patches, advisories, analysis.

scry

Attackers weaponise vulnerabilities like this against internet-exposed services. See what is exposed on your perimeter with a free passive scan.

Free scan