CVE-2026-31577: nilfs2: fix NULL i_assoc_inode dereference in nilfs_mdt_save_to_shadow_map
Vulnerability summary
CVE-2026-31577 is a medium (CVSS 5.5) NULL Pointer Dereference vulnerability in linux. EPSS estimates a 0.13% chance of exploitation in the next 30 days, higher than 2.2% 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 33 · Related 34Timeline
- 24-04-2026PublishedVulnerability first disclosed.
- 14-06-2026Last modifiedVulnerability information updated.
Description
In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix NULL i_assoc_inode dereference in nilfs_mdt_save_to_shadow_map The DAT inode's btree node cache (i_assoc_inode) is initialized lazily during btree operations. However, nilfs_mdt_save_to_shadow_map() assumes i_assoc_inode is already initialized when copying dirty pages to the shadow map during GC. If NILFS_IOCTL_CLEAN_SEGMENTS is called immediately after mount before any btree operation has occurred on the DAT inode, i_assoc_inode is NULL leading to a general protection fault. Fix this by calling nilfs_attach_btree_node_cache() on the DAT inode in nilfs_dat_read() at mount time, ensuring i_assoc_inode is always initialized before any GC operation can use it.
CVSS metrics
3 scores · 3 sources · 1 version- 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
0.13%
Chance of exploitation in the next 30 days
Percentile
2%
Versus all other CVEs
30-day change
Decrease -0.04 pp
From 0.17% 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.
Ubuntu154 products
- linuxAll versions (No fix recorded) | < 5.15.0-186.196 | < 6.8.0-136.136 | < 7.0.0-27.27
- linux-allwinner-5.19All versions (No fix recorded)
- linux-awsAll versions (No fix recorded) | < 5.15.0-1112.119 | < 6.8.0-1061.64 | < 7.0.0-1008.8
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Chainguard10 products
- linux-aws-6.12< 6.12.85-r0
- linux-aws-6.18< 6.18.31-r0
- linux-azure-6.18< 6.18.31-r0
- linux-gcp-6.12< 6.12.85-r0
- linux-gcp-6.18< 6.18.31-r0
Linux2 products
- linux≥ d626fcdabea2258be395a775bdbe09270e9bf73d, < 6637bbcfb59df5b732a79e5ab1a74886a0b93d59 | ≥ d05cc5395e36711edad8bdef6945f138d8a7097b, < 837c7a59fb58f81b0db33848357f6a5d0d1250ad | ≥ e897be17a441fa637cd166fc3de1445131e57692, < 7902b1df1520a0880bcda7a3704cfacd17905a83 | ≥ e897be17a441fa637cd166fc3de1445131e57692, < 7318e3549518ce8f14776a489d86488d80d7e2c8 | ≥ e897be17a441fa637cd166fc3de1445131e57692, < 449ec5fc99f45974525ba9eea16b6670c45cd363 | ≥ e897be17a441fa637cd166fc3de1445131e57692, < c36e206f302f1ddefed92d09ecbba070e1ae079e | ≥ e897be17a441fa637cd166fc3de1445131e57692, < 41de342278ae025c99cc8d33648773f05e306cf1 | ≥ e897be17a441fa637cd166fc3de1445131e57692, < 97fb7afec404912d967a7d4715f37742666b3084 | ≥ e897be17a441fa637cd166fc3de1445131e57692, < 4a4e0328edd9e9755843787d28f16dd4165f8b48 | 6c3da8c0a35bbafe359d9166269d5590f29664de | 605babb979c213737618b1c837e89624e5ab11fd | 307d021b1a7f33048b624f7aaeaa75e3eae571f1 | 1829b24a36ca12ca95b96d5478faeff40c17f2b6 | ≥ 5.10.118, < 5.10.258 | ≥ 5.15.42, < 5.15.209 | ≥ 4.14.296, < 4.15 | ≥ 4.19.245, < 4.20 | ≥ 5.4.196, < 5.5 | ≥ 5.17.10, < 5.18 | 5.18
- linux_kernel< 6.6.136 | ≥ 6.7, < 6.12.83 | ≥ 6.13, < 6.18.24 | ≥ 6.19, < 6.19.14 | ≥ 7.0, < 7.0.1
Debian1 product
- linux< 6.1.176-1 | < 6.12.85-1 | < 6.19.14-1
4 vendors · 167 products
