Bug 2467139 (CVE-2026-43266)

Summary: CVE-2026-43266 kernel: EFI/CPER: don't go past the ARM processor CPER record buffer
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's handling of Common Platform Error Records (CPER) for ARM processors. This vulnerability allows a local attacker or malicious firmware to provide a malformed CPER record with an excessively large section length. The kernel then attempts to read data beyond the intended memory buffer, which can lead to a system crash, causing a Denial of Service. This issue could also potentially disclose sensitive information from the kernel's memory.
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Description OSIDB Bzimport 2026-05-06 13:06:28 UTC 
In the Linux kernel, the following vulnerability has been resolved:

EFI/CPER: don't go past the ARM processor CPER record buffer

There's a logic inside GHES/CPER to detect if the section_length
is too small, but it doesn't detect if it is too big.

Currently, if the firmware receives an ARM processor CPER record
stating that a section length is big, kernel will blindly trust
section_length, producing a very long dump. For instance, a 67
bytes record with ERR_INFO_NUM set 46198 and section length
set to 854918320 would dump a lot of data going a way past the
firmware memory-mapped area.

Fix it by adding a logic to prevent it to go past the buffer
if ERR_INFO_NUM is too big, making it report instead:

	[Hardware Error]: Hardware error from APEI Generic Hardware Error Source: 1
	[Hardware Error]: event severity: recoverable
	[Hardware Error]:  Error 0, type: recoverable
	[Hardware Error]:   section_type: ARM processor error
	[Hardware Error]:   MIDR: 0xff304b2f8476870a
	[Hardware Error]:   section length: 854918320, CPER size: 67
	[Hardware Error]:   section length is too big
	[Hardware Error]:   firmware-generated error record is incorrect
	[Hardware Error]:   ERR_INFO_NUM is 46198

[ rjw: Subject and changelog tweaks ]
Comment 1 Keith Grant 2026-05-06 23:50:24 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026050608-CVE-2026-43266-506d@gregkh/T