What’s Vulnerable › Vulnerabilities

CVE-2026-31447: ext4: reject mount if bigalloc with s_first_data_block != 0

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-22 · updated 2026-10-19
• Weakness: CWE-20

Description

In the Linux kernel, the following vulnerability has been resolved: ext4: reject mount if bigalloc with s_first_data_block != 0 bigalloc with s_first_data_block != 0 is not supported, reject mounting it.

Affected products

• Linux kernel: from 3.2 before 5.10.253; from 5.11 before 5.15.203; from 5.16 before 6.1.168; from 6.2 before 6.6.131; from 6.7 before 6.12.80; from 6.13 before 6.18.21 — fixed in 5.10.253, 5.15.203, 6.1.168, 6.12.80, 6.18.21, 6.19.11

How to fix

Upgrade to a fixed version: Linux kernel 5.10.253, 5.15.203, 6.1.168, 6.12.80. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/3822743dc20386d9897e999dbb990befa3a5b3f8
• https://git.kernel.org/stable/c/3a926957cc95899ef88529710836edadc03c71a1
• https://git.kernel.org/stable/c/5ad6d994255e27a3254079dfb50ca861fc31f2d0
• https://git.kernel.org/stable/c/7b58c110b4e1f028eb38eec9ed3555e9be81c8b0
• https://git.kernel.org/stable/c/7d5b04290156c3fc316eecc86a4f9d201ab7d44a
• https://git.kernel.org/stable/c/ad1f6d608f33f59d21a3d025615d6786a6443998
• https://git.kernel.org/stable/c/b77de3fceafbb39f30e4ff5dc986f863d5456417
• https://git.kernel.org/stable/c/d787d3ae96648dc14a3b7ca8fde817177e82c1c7
• https://cert-portal.siemens.com/productcert/html/ssa-019113.html
• https://cert-portal.siemens.com/productcert/html/ssa-082556.html
• https://cert-portal.siemens.com/productcert/html/ssa-457936.html

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