CVE-2025-38220: ext4: only dirty folios when data journaling regular files
Vulnerability summary
CVE-2025-38220 is a medium (CVSS 5.5) NULL Pointer Dereference vulnerability in linux. EPSS estimates a 0.17% chance of exploitation in the next 30 days, higher than 5.8% of scored vulnerabilities.
Not severe (CVSS 5.5, local access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 42 · Related 38Timeline
- 04-07-2025PublishedVulnerability first disclosed.
- 11-05-2026Last modifiedVulnerability information updated.
Description
In the Linux kernel, the following vulnerability has been resolved: ext4: only dirty folios when data journaling regular files fstest generic/388 occasionally reproduces a crash that looks as follows: BUG: kernel NULL pointer dereference, address: 0000000000000000 ... Call Trace: <TASK> ext4_block_zero_page_range+0x30c/0x380 [ext4] ext4_truncate+0x436/0x440 [ext4] ext4_process_orphan+0x5d/0x110 [ext4] ext4_orphan_cleanup+0x124/0x4f0 [ext4] ext4_fill_super+0x262d/0x3110 [ext4] get_tree_bdev_flags+0x132/0x1d0 vfs_get_tree+0x26/0xd0 vfs_cmd_create+0x59/0xe0 __do_sys_fsconfig+0x4ed/0x6b0 do_syscall_64+0x82/0x170 ... This occurs when processing a symlink inode from the orphan list. The partial block zeroing code in the truncate path calls ext4_dirty_journalled_data() -> folio_mark_dirty(). The latter calls mapping->a_ops->dirty_folio(), but symlink inodes are not assigned an a_ops vector in ext4, hence the crash. To avoid this problem, update the ext4_dirty_journalled_data() helper to only mark the folio dirty on regular files (for which a_ops is assigned). This also matches the journaling logic in the ext4_symlink() creation path, where ext4_handle_dirty_metadata() is called directly.
CVSS metrics
4 scores · 3 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.17%
Chance of exploitation in the next 30 days
Percentile
6%
Versus all other CVEs
30-day change
Increase +0.01 pp
From 0.15% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu120 products
- linux< 6.8.0-100.100
- linux-allwinner-5.19All versions (No fix recorded)
- linux-aws< 6.8.0-1046.49
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Linux2 products
- linux≥ d84c9ebdac1e39bc7b036c0c829ee8c1956edabc, < cf6a4c4ac7b6e3214f25df594c9689a62f1bb456 | ≥ d84c9ebdac1e39bc7b036c0c829ee8c1956edabc, < be5f3061a6f904e3674257879e71881ceee5b673 | ≥ d84c9ebdac1e39bc7b036c0c829ee8c1956edabc, < d7af6eee8cd60f55aa8c5fe2b91f11ec0c9a0f27 | ≥ d84c9ebdac1e39bc7b036c0c829ee8c1956edabc, < e26268ff1dcae5662c1b96c35f18cfa6ab73d9de | 6.4
- linux_kernel≥ 6.4, < 6.6.95 | ≥ 6.7, < 6.12.35 | ≥ 6.13, < 6.15.4
Debian1 product
- linux< 6.12.35-1
3 vendors · 123 products
