Linux Kernel up to 6.18.52 MMC Core mmc_mq_init_request sg_len memory corruption

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
3.7	$0-$5k	0.41

Summaryinfo

A vulnerability classified as problematic was found in Linux Kernel up to 5.15.221/6.1.188/6.6.157/6.12.110/6.18.52. Affected is the function mmc_mq_init_request of the component MMC Core. The manipulation of the argument sg_len results in memory corruption. This vulnerability is cataloged as CVE-2026-98884. The attack may be launched remotely. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as problematic has been found in Linux Kernel up to 5.15.221/6.1.188/6.6.157/6.12.110/6.18.52. Affected is the function mmc_mq_init_request of the component MMC Core. The manipulation of the argument sg_len with an unknown input leads to a memory corruption vulnerability. CWE is classifying the issue as CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer. This is going to have an impact on integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: mmc: core: Add validation for host-provided max_segs The max_segs field is of type unsigned short, and if a host driver sets an excessively large value, it may be truncated to zero. This can cause mmc_alloc_sg() to call kmalloc_objs() with a zero size allocation request, which leads to undefined behavior. Under the SLUB allocator, kmalloc(0) returns a special pointer (ZERO_SIZE_PTR). The subsequent 'if (sg)' check will evaluate to true, and sg_init_table() will then attempt to access invalid memory, resulting in a crash: dwmmc_rockchip 2a310000.mmc: Successfully tuned phase to 133 mmc1: new UHS-I speed SDR104 SDHC card at address aaaa Unable to handle kernel paging request at virtual address 0000001ffffffff0 Mem abort info: ESR = 0x0000000096000004 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x04: level 0 translation fault Data abort info: ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000 CM = 0, WnR = 0, TnD = 0, TagAccess = 0 GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 user pgtable: 4k pages, 48-bit VAs, pgdp=0000000102c88000 [0000001ffffffff0] pgd=0000000000000000, p4d=0000000000000000 Internal error: Oops: 0000000096000004 [#1] SMP Modules linked in: CPU: 2 UID: 0 PID: 102 Comm: kworker/2:1 Not tainted 7.0.0-rc6-next-20260331-00013-g4d93c25963c5-dirty #80 PREEMPT Hardware name: Rockchip RK3576 EVB V10 Board (DT) Workqueue: events_freezable mmc_rescan pstate: 80000005 (Nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : sg_init_table+0x2c/0x50 lr : sg_init_table+0x24/0x50 sp : ffff8000837db710 x29: ffff8000837db710 x28: 000000000000c000 x27: 0000000000000300 x26: 0000000000000000 x25: 0000000000000040 x24: ffff0000c46a0000 x23: 0000000000000000 x22: ffff0000c0c73c00 x21: 0000000000000010 x20: 0000000000000010 x19: 0000000000000000 x18: 000000000000002c x17: 0000000000000000 x16: 0000000000000001 x15: 0000000000000000 x14: 0000000000000400 x13: ffff8000837dc000 x12: 0000000000000000 x11: ffff0000c0c73ca0 x10: 0000000000000040 x9 : 459ec1f0abbdbb00 x8 : 0000001fffffffe0 x7 : 0000000000000000 x6 : 000000000000003f x5 : 0000000000035579 x4 : 0000000000000901 x3 : 0000000000000000 x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000010 Call trace: sg_init_table+0x2c/0x50 (P) mmc_mq_init_request+0x64/0x90 blk_mq_alloc_map_and_rqs+0x3ac/0x480 blk_mq_alloc_set_map_and_rqs+0x98/0x1e0 blk_mq_alloc_tag_set+0x1c0/0x290 mmc_init_queue+0x120/0x370 mmc_blk_alloc_req+0x150/0x420 To prevent this, add a validation check in mmc_mq_init_request() to detect when sg_len (derived from max_segs) is zero. If sg_len is zero, we return an error and print an error message, allowing host driver developers to identify and fix incorrect max_segs configuration. This is a defensive measure that ensures the MMC core fails gracefully when host drivers provide invalid max_segs values, rather than crashing with a page fault.

The advisory is available at git.kernel.org. This vulnerability is traded as CVE-2026-98884 since 09/25/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. Additional levels of successful authentication are needed for exploitation. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 10/23/2026).

Upgrading to version 5.15.222, 6.1.189, 6.6.158, 6.12.111 or 6.18.53 eliminates this vulnerability. Applying the patch 03f5a16ec85beebabd5ab5e67ac1527f87908ded/c465608bd25d7f8565be7817a6a36a5d69f8aa14/a8283f7d93f0d9336b15618b9665279ff6944319/9cca3c0c1472d6204ef8a78a6e7b3afe9610b22e/b037c2f7794aa01ee2a00e43c29645fd2dd2dfb9/3e0483e93a8be320f70a1ff68d835f7f015af311 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

• 5.15.221
• 6.1.188
• 6.6.157
• 6.12.110
• 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
• 6.18.52

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: 3.8
VulDB Meta Temp Score: 3.7

VulDB Base Score: 3.8
VulDB Temp Score: 3.7
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: Memory corruption
CWE: CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

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

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.15.222/6.1.189/6.6.158/6.12.111/6.18.53
Patch: 03f5a16ec85beebabd5ab5e67ac1527f87908ded/c465608bd25d7f8565be7817a6a36a5d69f8aa14/a8283f7d93f0d9336b15618b9665279ff6944319/9cca3c0c1472d6204ef8a78a6e7b3afe9610b22e/b037c2f7794aa01ee2a00e43c29645fd2dd2dfb9/3e0483e93a8be320f70a1ff68d835f7f015af311

Timelineinfo

09/25/2026 CVE reserved
10/23/2026 +28 days Advisory disclosed
10/23/2026 +0 days VulDB entry created
10/23/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-98884 (🔒)
GCVE (CVE): GCVE-0-2026-98884
GCVE (VulDB): GCVE-100-425754

Entryinfo

Created: 10/23/2026 14:57
Changes: 10/23/2026 14:57 (60)
Complete: 🔍
Cache ID: 216::103

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