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CVE-2024-49940— l2tp: prevent possible tunnel refcount underflow

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l2tp组件中隧道引用计数下溢问题。

CVSS 7.8 · High EPSS 0.24% · P14

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 16

VendorProduct Version RangeStatus
Linux Linux 3953ae7b218df4d1e544b98a393666f9ae58a78c< f7415e60c25a6108cd7955a20b2e66b6251ffe02 affected
3953ae7b218df4d1e544b98a393666f9ae58a78c< 24256415d18695b46da06c93135f5b51c548b950 affected
b102bfc2a90d14f342580285782a9a51c74f7369 affected
10c15ddabbcf888922adbdd44ca3fecf6eab19d9 affected
8d1c650d452c53fcb3f02a7b1d772741639f89a4 affected
12b5fb58ac993c24210cf8cbc72d407d3a4e6490 affected
aef37401b467a0b1a9517c69924a1d66937e0789 affected
3.2.99< 3.3 affected
… +8 more rows
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I. Basic Information for CVE-2024-49940

Vulnerability Information
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Vulnerability Title
l2tp: prevent possible tunnel refcount underflow
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: l2tp: prevent possible tunnel refcount underflow When a session is created, it sets a backpointer to its tunnel. When the session refcount drops to 0, l2tp_session_free drops the tunnel refcount if session->tunnel is non-NULL. However, session->tunnel is set in l2tp_session_create, before the tunnel refcount is incremented by l2tp_session_register, which leaves a small window where session->tunnel is non-NULL when the tunnel refcount hasn't been bumped. Moving the assignment to l2tp_session_register is trivial but l2tp_session_create calls l2tp_session_set_header_len which uses session->tunnel to get the tunnel's encap. Add an encap arg to l2tp_session_set_header_len to avoid using session->tunnel. If l2tpv3 sessions have colliding IDs, it is possible for l2tp_v3_session_get to race with l2tp_session_register and fetch a session which doesn't yet have session->tunnel set. Add a check for this case.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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l2tp组件中隧道引用计数下溢问题。
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 3953ae7b218df4d1e544b98a393666f9ae58a78c ~ 98691b2e28a6c3dac0680914493d54c77f215755 -
Linux Linux 4.15 -

II. Public POCs for CVE-2024-49940

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III. Intelligence Information for CVE-2024-49940

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Patches & Fixes for CVE-2024-49940 (1)

Other References for CVE-2024-49940 (1)

Same Patch Batch · Linux · 2024-10-21 · 372 CVEs total

CVE-2022-48985 9.8 CRITICAL net: mana: Fix race on per-CQ variable napi work_done
CVE-2024-50033 9.8 CRITICAL slip: make slhc_remember() more robust against malicious packets
CVE-2024-47695 9.8 CRITICAL RDMA/rtrs-clt: Reset cid to con_num - 1 to stay in bounds
CVE-2024-50043 9.8 CRITICAL nfsd: fix possible badness in FREE_STATEID
CVE-2024-49855 9.8 CRITICAL nbd: fix race between timeout and normal completion
CVE-2024-50047 9.8 CRITICAL smb: client: fix UAF in async decryption
CVE-2024-50046 9.8 CRITICAL NFSv4: Prevent NULL-pointer dereference in nfs42_complete_copies()
CVE-2022-49003 9.8 CRITICAL nvme: fix SRCU protection of nvme_ns_head list
CVE-2024-49996 9.4 CRITICAL cifs: Fix buffer overflow when parsing NFS reparse points
CVE-2024-47678 9.4 CRITICAL icmp: change the order of rate limits
CVE-2024-49939 8.8 HIGH wifi: rtw89: avoid to add interface to list twice when SER
CVE-2024-49936 8.8 HIGH net/xen-netback: prevent UAF in xenvif_flush_hash()
CVE-2024-50029 8.8 HIGH Bluetooth: hci_conn: Fix UAF in hci_enhanced_setup_sync
CVE-2022-49017 8.8 HIGH tipc: re-fetch skb cb after tipc_msg_validate
CVE-2022-48962 8.8 HIGH net: hisilicon: Fix potential use-after-free in hisi_femac_rx()
CVE-2022-49015 8.8 HIGH net: hsr: Fix potential use-after-free
CVE-2022-48964 8.8 HIGH ravb: Fix potential use-after-free in ravb_rx_gbeth()
CVE-2024-49950 8.8 HIGH Bluetooth: L2CAP: Fix uaf in l2cap_connect
CVE-2022-48967 8.8 HIGH NFC: nci: Bounds check struct nfc_target arrays
CVE-2024-50041 8.8 HIGH i40e: Fix macvlan leak by synchronizing access to mac_filter_hash

Showing top 20 of 372 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2024-49940

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