Bug 2532509 (CVE-2026-89525)

Summary:	CVE-2026-89525 kernel: Linux kernel: Denial of Service via out-of-bounds read in UDF virtual partition mapping
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, sghai, sidsharm, suppawar, vlaad
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel. A local attacker could craft a malicious Universal Disk Format (UDF) image to trigger an out-of-bounds read vulnerability in the `udf_get_pblock_virt15()` function. This occurs when the system attempts to read a Virtual Allocation Table (VAT) index equal to the entry count, bypassing a bounds check. This can lead to reading memory beyond the allocated table, potentially causing a kernel panic and a denial of service.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-11 23:33:36 UTC

In the Linux kernel, the following vulnerability has been resolved:

udf: reject VAT indexes equal to the entry count

UDF 1.50 virtual partition mapping uses the VAT as an array of physical
block mappings. s_num_entries stores the number of entries in that array,
not the highest valid index. The valid VAT indexes are therefore below
s_num_entries.

udf_get_pblock_virt15() currently rejects only indexes greater than
s_num_entries. A crafted image can request index s_num_entries, pass the
bounds check, and make the kernel read one entry past the allocated VAT table.

Change the check to reject block >= s_num_entries, so the count is handled as
an exclusive upper bound.

A crafted UDF image reproduced this on origin/master commit
0e35b9b6ec0ffcc5e23cbdec09f5c622ad532b53 with a KASAN slab-out-of-bounds
report in udf_get_pblock_virt15().

Trail of Bits has a reproducer that triggers kernel panic demonstrating the bug, and can share it if needed.