5.5

CVE-2026-52940: linux

CVSS: 5.5v3.1MediumAnalyzed
AliasesUBUNTU-CVE-2026-52940DEBIAN-CVE-2026-52940CGA-52rg-rhmf-vv3h
Published 24-06-2026Last modified 24-06-2026
Open JSON

Vulnerability summary

CVE-2026-52940 is a medium (CVSS 5.5) vulnerability in linux. EPSS estimates a 0.11% chance of exploitation in the next 30 days, higher than 1.3% of scored vulnerabilities.

Overall risk
22/100
0100
Low · default modelHow is this calculated?
CVSS score
5.5/10
010
Medium · v3.1 (NVD)
EPSS score
0.11%
0%100%
Low · -0.05 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 12 · Related 12
MGASA-2026-0312USN-8726-1USN-8726-2USN-8726-3USN-8726-4USN-8727-1

Timeline

  1. 24-06-2026
    PublishedVulnerability first disclosed.

Description

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.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.11%

Chance of exploitation in the next 30 days

Percentile

1%

Versus all other CVEs

30-day change

-0.05 pp

From 0.16% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.11%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

No weakness data has been published for this record.

Affected systems

Ubuntu119 products
  • linuxAll versions (No fix recorded) | < 7.0.0-31.31
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-awsAll versions (No fix recorded) | < 7.0.0-1012.12
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Chainguard6 products
  • linux-azure-6.18< 6.18.38-r0
  • linux-gcp-6.18< 6.18.38-r0
  • linux-gcp-6.18-bootc-boot-installed< 6.18.38-r0
  • linux-qemu-6.18< 6.18.38-r0
  • linux-qemu-6.18-bootc-boot-installed< 6.18.38-r0
Linux2 products
  • linux≥ 288f30435132d2f9e7a29ec9b9745a4f9dc7fd37, < 5fd1fa5a4254bfdd70571c77f5e3bcb4e43738d5 | ≥ 288f30435132d2f9e7a29ec9b9745a4f9dc7fd37, < 585cb85e9a29185be05f326369573c2663cf4380 | ≥ 288f30435132d2f9e7a29ec9b9745a4f9dc7fd37, < 7f2fcff15e99bb852f6967396ed12b38376e2c8d | 6.17
  • linux_kernel≥ 6.17, < 6.18.36 | ≥ 6.19, < 7.0.13 | 7.1:rc1 | 7.1:rc2 | 7.1:rc3 | 7.1:rc4 | 7.1:rc5 | 7.1:rc6 | 7.1:rc7
Debian1 product
  • linux< 7.0.13-1

4 vendors · 128 products

References

18 links
Show all 18 references