Linux Kernel up to 6.6.156/6.12.109/6.18.51/7.2.5 powerpc/irq call_do_irq/call_do_softirq stack-based overflow

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6.2	$5k-$25k	0.00+

Summaryinfo

A vulnerability identified as critical has been detected in Linux Kernel up to 6.6.156/6.12.109/6.18.51/7.2.5. The affected element is the function call_do_irq/call_do_softirq of the component powerpc/irq. The manipulation leads to stack-based overflow. This vulnerability is documented as CVE-2026-93259. The attack can be initiated remotely. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.6.156/6.12.109/6.18.51/7.2.5. It has been rated as critical. This issue affects the function call_do_irq/call_do_softirq of the component powerpc/irq. The manipulation with an unknown input leads to a stack-based overflow vulnerability. Using CWE to declare the problem leads to CWE-121. A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function). Impacted is integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: powerpc/irq: Fix missing r2 clobber in PCREL inline assembly In CONFIG_PPC_KERNEL_PCREL mode, r2 is no longer reserved for the TOC pointer and is available as a caller-saved register [0]. Both call_do_irq() and call_do_softirq() use inline assembly to call functions with stack switching, but fail to list r2 in their clobber lists. This causes the compiler to assume r2 is preserved across these calls, leading to register corruption when the called functions (__do_irq and __do_softirq) clobber r2. As a result of this kernel crash during interrupt handling is seen and the kernel fails to boot: BUG: Unable to handle kernel data access on write at 0xc000000404697638 Faulting instruction address: 0xc0000000000181ec Oops: Kernel access of bad area, sig: 11 [#1] NIP [c0000000000181ec] __do_IRQ+0x6c/0xc0 With older GCC, the compiler would conservatively allocate callee-saved registers (like r31) for values spanning function calls, accidentally avoiding the bug: <__do_IRQ>: 00 00 00 60 nop a6 02 08 7c mflr r0 f8 ff e1 fb std r31,-8(r1) f0 ff c1 fb std r30,-16(r1) 2d 03 10 06 pla r31,53297316 ... 3d e8 ff 4b bl c0000000000165ac <__do_irq> 00 00 21 e8 ld r1,0(r1) 28 00 4d e9 ld r10,40(r13) 40 00 21 38 addi r1,r1,64 2a f9 aa 7f stdx r29,r10,r31 With newer GCC 14, the compiler uses r2 for such values, exposing the missing clobber specification: <__do_IRQ>: 00 00 00 60 nop a6 02 08 7c mflr r0 f0 ff c1 fb std r30,-16(r1) f8 ff e1 fb std r31,-8(r1) 29 02 10 06 pla r2,36252592 # c0000000022aadc0 <__irq_regs> ... 85 dc ff 4b bl c000000000015ee0 <__do_irq> 00 00 21 e8 ld r1,0(r1) 28 00 2d e9 ld r9,40(r13) 30 00 21 38 addi r1,r1,48 2a 11 c9 7f stdx r30,r9,r2 Fix this by adding r2 to the clobber list for both call_do_irq() and call_do_softirq() when CONFIG_PPC_KERNEL_PCREL is enabled. [0]: https://www.mail-archive.com/[email protected]/msg313226.html

The advisory is shared at git.kernel.org. The identification of this vulnerability is CVE-2026-93259 since 09/17/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are known, but no exploit is available. The price for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 09/24/2026).

Upgrading to version 6.6.157, 6.12.110, 6.18.52, 7.2.6 or 7.3-rc1 eliminates this vulnerability. Applying the patch dcc442a49c0f540193910dacdca7506bcadc7ec5/602ee44415f3eaa7893f7fc488c7c1d4a0bdbd7a/90d953002cf0b233dd053a0e7cb67ab79cebd0e3/7b0093b638c8f2b94b0778a69fd1ccad54299b29/00be69070d91d2be978e752bb117a0a4db0e1281 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.6.156
• 6.12.109
• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
• 6.18.10
• 6.18.11
• 6.18.12
• 6.18.13
• 6.18.14
• 6.18.15
• 6.18.16
• 6.18.17
• 6.18.18
• 6.18.19
• 6.18.20
• 6.18.21
• 6.18.22
• 6.18.23
• 6.18.24
• 6.18.25
• 6.18.26
• 6.18.27
• 6.18.28
• 6.18.29
• 6.18.30
• 6.18.31
• 6.18.32
• 6.18.33
• 6.18.34
• 6.18.35
• 6.18.36
• 6.18.37
• 6.18.38
• 6.18.39
• 6.18.40
• 6.18.41
• 6.18.42
• 6.18.43
• 6.18.44
• 6.18.45
• 6.18.46
• 6.18.47
• 6.18.48
• 6.18.49
• 6.18.50
• 6.18.51
• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.3
• 7.2.4
• 7.2.5

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.5
VulDB Meta Temp Score: 6.2

VulDB Base Score: 6.5
VulDB Temp Score: 6.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Stack-based overflow
CWE: CWE-121 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.6.157/6.12.110/6.18.52/7.2.6/7.3-rc1
Patch: dcc442a49c0f540193910dacdca7506bcadc7ec5/602ee44415f3eaa7893f7fc488c7c1d4a0bdbd7a/90d953002cf0b233dd053a0e7cb67ab79cebd0e3/7b0093b638c8f2b94b0778a69fd1ccad54299b29/00be69070d91d2be978e752bb117a0a4db0e1281

Timelineinfo

09/17/2026 CVE reserved
09/24/2026 +7 days Advisory disclosed
09/24/2026 +0 days VulDB entry created
09/24/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-93259 (🔒)
GCVE (CVE): GCVE-0-2026-93259
GCVE (VulDB): GCVE-100-409481

Entryinfo

Created: 09/24/2026 18:32
Changes: 09/24/2026 18:32 (59)
Complete: 🔍
Cache ID: 216::103

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Discussion

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