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CVE-2021-4439— isdn: cpai: check ctr->cnr to avoid array index out of bound

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel 存在安全漏洞，该漏洞源于 isdn:cpai 模块数组索引越界。

AI Predicted 5.5 Difficulty: Moderate EPSS 0.24% · P13

Possible ATT&CK Techniques 1 AI

T1203 · Exploitation for Client Execution

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< e8b8de17e164c9f1b7777f1c6f99d05539000036 affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 24219a977bfe3d658687e45615c70998acdbac5a affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 9b6b2db77bc3121fe435f1d4b56e34de443bec75 affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 7d91adc0ccb060ce564103315189466eb822cc6a affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 285e9210b1fab96a11c0be3ed5cea9dd48b6ac54 affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 7f221ccbee4ec662e2292d490a43ce6c314c4594 affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< cc20226e218a2375d50dd9ac14fb4121b43375ff affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 1f3e2e97c003f80c4b087092b225c8787ff91e4d affected
… +10 more rows
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I. Basic Information for CVE-2021-4439

Vulnerability Information
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Vulnerability Title
isdn: cpai: check ctr->cnr to avoid array index out of bound
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: isdn: cpai: check ctr->cnr to avoid array index out of bound The cmtp_add_connection() would add a cmtp session to a controller and run a kernel thread to process cmtp. __module_get(THIS_MODULE); session->task = kthread_run(cmtp_session, session, "kcmtpd_ctr_%d", session->num); During this process, the kernel thread would call detach_capi_ctr() to detach a register controller. if the controller was not attached yet, detach_capi_ctr() would trigger an array-index-out-bounds bug. [ 46.866069][ T6479] UBSAN: array-index-out-of-bounds in drivers/isdn/capi/kcapi.c:483:21 [ 46.867196][ T6479] index -1 is out of range for type 'capi_ctr *[32]' [ 46.867982][ T6479] CPU: 1 PID: 6479 Comm: kcmtpd_ctr_0 Not tainted 5.15.0-rc2+ #8 [ 46.869002][ T6479] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 [ 46.870107][ T6479] Call Trace: [ 46.870473][ T6479] dump_stack_lvl+0x57/0x7d [ 46.870974][ T6479] ubsan_epilogue+0x5/0x40 [ 46.871458][ T6479] __ubsan_handle_out_of_bounds.cold+0x43/0x48 [ 46.872135][ T6479] detach_capi_ctr+0x64/0xc0 [ 46.872639][ T6479] cmtp_session+0x5c8/0x5d0 [ 46.873131][ T6479] ? __init_waitqueue_head+0x60/0x60 [ 46.873712][ T6479] ? cmtp_add_msgpart+0x120/0x120 [ 46.874256][ T6479] kthread+0x147/0x170 [ 46.874709][ T6479] ? set_kthread_struct+0x40/0x40 [ 46.875248][ T6479] ret_from_fork+0x1f/0x30 [ 46.875773][ T6479]
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel 存在安全漏洞，该漏洞源于 isdn:cpai 模块数组索引越界。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 ~ e8b8de17e164c9f1b7777f1c6f99d05539000036 -
Linux Linux 2.6.12 -

II. Public POCs for CVE-2021-4439

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III. Intelligence Information for CVE-2021-4439

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Other References for CVE-2021-4439 (8)

Same Patch Batch · Linux · 2024-06-20 · 67 CVEs total

CVE-2022-48711 9.8 CRITICAL tipc: improve size validations for received domain records
CVE-2024-38620 8.8 HIGH Bluetooth: HCI: Remove HCI_AMP support
CVE-2021-47620 8.1 HIGH Bluetooth: refactor malicious adv data check
CVE-2022-48743 8.1 HIGH net: amd-xgbe: Fix skb data length underflow
CVE-2022-48720 7.8 HIGH net: macsec: Fix offload support for NETDEV_UNREGISTER event
CVE-2022-48751 7.8 HIGH net/smc: Transitional solution for clcsock race issue
CVE-2022-48733 7.8 HIGH btrfs: fix use-after-free after failure to create a snapshot
CVE-2022-48716 7.8 HIGH ASoC: codecs: wcd938x: fix incorrect used of portid
CVE-2022-48771 7.8 HIGH drm/vmwgfx: Fix stale file descriptors on failed usercopy
CVE-2022-48729 7.8 HIGH IB/hfi1: Fix panic with larger ipoib send_queue_size
CVE-2022-48759 7.8 HIGH rpmsg: char: Fix race between the release of rpmsg_ctrldev and cdev
CVE-2022-48742 7.8 HIGH rtnetlink: make sure to refresh master_dev/m_ops in __rtnl_newlink()
CVE-2022-48721 7.8 HIGH net/smc: Forward wakeup to smc socket waitqueue after fallback
CVE-2022-48762 7.8 HIGH arm64: extable: fix load_unaligned_zeropad() reg indices
CVE-2022-48754 7.8 HIGH phylib: fix potential use-after-free
CVE-2022-48735 7.8 HIGH ALSA: hda: Fix UAF of leds class devs at unbinding
CVE-2022-48726 7.8 HIGH RDMA/ucma: Protect mc during concurrent multicast leaves
CVE-2022-48744 7.5 HIGH net/mlx5e: Avoid field-overflowing memcpy()
CVE-2022-48727 7.3 HIGH KVM: arm64: Avoid consuming a stale esr value when SError occur
CVE-2022-48717 7.1 HIGH ASoC: max9759: fix underflow in speaker_gain_control_put()

Showing top 20 of 67 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2021-4439

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