CVE-2025-37858: Debian Linux

Medium severity, CVSS 5.5. EPSS: 0.3% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: fs/jfs: Prevent integer overflow in AG size calculation The JFS filesystem calculates allocation group (AG) size using 1 << l2agsize in dbExtendFS(). When l2agsize exceeds 31 (possible with >2TB aggregates on 32-bit systems), this 32-bit shift operation causes undefined behavior and improper AG sizing. On 32-bit architectures: - Left-shifting 1 by 32+ bits results in 0 due to integer overflow - This creates invalid AG sizes (0 or garbage values) in sbi->bmap->db_agsize - Subsequent block allocations would reference invalid AG structures - Could lead to: - Filesystem corruption during extend operations - Kernel crashes due to invalid memory accesses - Security vulnerabilities via malformed on-disk structures Fix by casting to s64 before shifting: bmp->db_agsize = (s64)1 << l2agsize; This ensures 64-bit arithmetic even on 32-bit architectures. The cast matches the data type of db_agsize (s64) and follows similar patterns in JFS block calculation code. Found by Linux Verification Center (linuxtesting.org) with SVACE.

Affected products

• Debian Debian Linux: version 11.0 only
• Linux Linux Kernel: before 5.4.293 (fixed in 5.4.293); from 5.5, before 5.10.237 (fixed in 5.10.237); from 5.11, before 5.15.181 (fixed in 5.15.181); from 5.16, before 6.1.135 (fixed in 6.1.135); from 6.2, before 6.6.88 (fixed in 6.6.88); from 6.7, before 6.12.24 (fixed in 6.12.24); …

Published 2025-05-09. Last modified 2026-06-17.