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Vulnerability record · CVE-2026-45991 · published 27 May 2026

CVE-2026-45991: Linux kernel out-of-bounds write vulnerability

Linux · Linux Kernel

In the Linux kernel, the following vulnerability has been resolved: udf: fix partition descriptor append bookkeeping Mounting a crafted UDF image with repeated partition descriptors can trigger a heap out-of-bounds write in part_descs_loc[]. handle_partition_descriptor() deduplicates entries by partition number, but appended slots never record partnum. As a result duplicate Partition Descriptors are appended repeatedly and num_part_descs keeps growing. Once the table is full, the growth path still sizes the allocation from partnum even though inserts are indexed by num_part_descs. If partnum is already aligned to PART_DESC_ALLOC_STEP, ALIGN(partnum, step) can keep the old capacity and the next append writes past the end of the table. Store partnum in the appended slot and size growth from the next append count so deduplication and capacity tracking follow the same model.

7.8 CVSS 3.1 High EPSS 0.18% · top 93.7% CWE-787 · Out-of-bounds write
7.8CVSS 3.1 base score
0.18%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
7References
19 Jun 2026Last modified by NVD

Description

In the Linux kernel, the following vulnerability has been resolved: udf: fix partition descriptor append bookkeeping Mounting a crafted UDF image with repeated partition descriptors can trigger a heap out-of-bounds write in part_descs_loc[]. handle_partition_descriptor() deduplicates entries by partition number, but appended slots never record partnum. As a result duplicate Partition Descriptors are appended repeatedly and num_part_descs keeps growing. Once the table is full, the growth path still sizes the allocation from partnum even though inserts are indexed by num_part_descs. If partnum is already aligned to PART_DESC_ALLOC_STEP, ALIGN(partnum, step) can keep the old capacity and the next append writes past the end of the table. Store partnum in the appended slot and size growth from the next append count so deduplication and capacity tracking follow the same model.

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://git.kernel.org/stable/c/058b451b1039f056d1362c4fec2229e522366ab0 Patch
https://git.kernel.org/stable/c/08841b06fa64d8edbd1a21ca6e613420c90cc4b8 Patch
https://git.kernel.org/stable/c/08fa5d818e5bf53c7ca234d88ba334f32004e9b6 Patch
https://git.kernel.org/stable/c/68013a9bd4c01acd42073715f00e1a1992f089ee
https://git.kernel.org/stable/c/ad3c0c4400686f6f37b382aaa48fac2b9aefccbe
https://git.kernel.org/stable/c/b5597bb83fc37b5b5da74a4453fa920b932cf39a Patch
https://git.kernel.org/stable/c/e8474cfbac9ada2cdaa4eaedec22aadfa0f58559

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Source: NIST National Vulnerability Database (record CVE-2026-45991), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.