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CVE-2026-53262— l2tp: pppol2tp: hold reference to session in pppol2tp_ioctl()

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基金会开源的操作系统Linux所使用的内核。 Linux kernel 2.6.35版本存在安全漏洞，该漏洞源于pppol2tp_ioctl()函数直接读取sock->sk->sk_user_data而未使用锁或引用计数，可能导致释放后重用。

CVSS 7.8 · High EPSS 0.12% · P2

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux fd558d186df2c13a22455373858bae634a4795af< 78cdfdca88cbf731a92f3b9ee5427c633dd94e28 affected
fd558d186df2c13a22455373858bae634a4795af< e251d4cdfc725c9e7d686161e3b775a0e7d95053 affected
fd558d186df2c13a22455373858bae634a4795af< 62f327e287cf7b595ae3f73ba72f5cd2a9e9f39f affected
fd558d186df2c13a22455373858bae634a4795af< a213a8950414c684999dcf03edeea6c46ede172e affected
2.6.35 affected
< 2.6.35 unaffected
6.12.94≤ 6.12.* unaffected
6.18.36≤ 6.18.* unaffected
… +2 more rows
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I. Basic Information for CVE-2026-53262

Vulnerability Information
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Vulnerability Title
l2tp: pppol2tp: hold reference to session in pppol2tp_ioctl()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: l2tp: pppol2tp: hold reference to session in pppol2tp_ioctl() pppol2tp_ioctl() read sock->sk->sk_user_data directly without any locks or reference counting. If a controllable sleep was induced during copy_from_user() (e.g. via a userfaultfd page fault sleep), a concurrent socket close could trigger pppol2tp_session_close() asynchronously. This frees the l2tp_session structure via the l2tp_session_del_work workqueue. Upon resuming, the ioctl thread dereferences the stale session pointer, resulting in a Use-After-Free (UAF). Fix this by securely fetching the session reference using the RCU-safe, refcounted helper pppol2tp_sock_to_session(sk) on entry. This locks the session's refcount across the sleep. We structured the function to exit via standard err breaks, guaranteeing that l2tp_session_put() is cleanly called on all return paths to drop the reference. To preserve existing behavior we validate the session and its magic signature only for the specific L2TP commands that require it. This ensures that generic/unknown ioctls called on an unconnected socket still return -ENOIOCTLCMD and correctly fall back to generic handlers (e.g. in sock_do_ioctl()).
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基金会开源的操作系统Linux所使用的内核。 Linux kernel 2.6.35版本存在安全漏洞，该漏洞源于pppol2tp_ioctl()函数直接读取sock->sk->sk_user_data而未使用锁或引用计数，可能导致释放后重用。
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 fd558d186df2c13a22455373858bae634a4795af ~ 78cdfdca88cbf731a92f3b9ee5427c633dd94e28 -
Linux Linux 2.6.35 -

II. Public POCs for CVE-2026-53262

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III. Intelligence Information for CVE-2026-53262

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Patches & Fixes for CVE-2026-53262 (4)

Same Patch Batch · Linux · 2026-06-25 · 146 CVEs total

CVE-2026-53175 9.8 CRITICAL inet: frags: fix use-after-free caused by the fqdir_pre_exit() flush
CVE-2026-53176 9.8 CRITICAL IB/isert: Reject login PDUs shorter than ISER_HEADERS_LEN
CVE-2026-53228 9.8 CRITICAL ipv6: sit: reload inner IPv6 header after GSO offloads
CVE-2026-53221 9.8 CRITICAL ip6_vti: fix incorrect tunnel matching in vti6_tnl_lookup()
CVE-2026-53246 9.8 CRITICAL sctp: validate cached peer INIT chunk length in COOKIE_ECHO processing
CVE-2026-53247 9.8 CRITICAL net: ethernet: mtk_eth_soc: Fix use-after-free in metadata dst teardown
CVE-2026-53151 9.8 CRITICAL rxrpc: Fix the ACK parser to extract the SACK table for parsing
CVE-2026-53216 9.8 CRITICAL net: mvpp2: limit XDP frame size to the RX buffer
CVE-2026-53260 9.8 CRITICAL tcp: Add preempt_{disable,enable}_nested() in reqsk_queue_hash_req().
CVE-2026-53215 9.8 CRITICAL net: mvpp2: refill RX buffers before XDP or skb use
CVE-2026-53131 9.4 CRITICAL netfilter: require Ethernet MAC header before using eth_hdr()
CVE-2026-53225 9.1 CRITICAL sctp: fix uninit-value in __sctp_rcv_asconf_lookup()
CVE-2026-53224 9.1 CRITICAL sctp: validate embedded INIT chunk and address list lengths in cookie
CVE-2026-53186 9.1 CRITICAL RDMA/srp: bound SRP_RSP sense copy by the received length
CVE-2026-53159 8.8 HIGH misc: fastrpc: fix DMA address corruption due to find_vma misuse
CVE-2026-53198 8.8 HIGH ksmbd: fix use-after-free of a deferred file_lock on double SMB2_CANCEL
CVE-2026-53240 8.8 HIGH xfrm: iptfs: fix use-after-free on first_skb in __input_process_payload
CVE-2026-53275 8.8 HIGH ipv6: mcast: Fix use-after-free when processing MLD queries
CVE-2026-53188 8.8 HIGH RDMA/core: Validate the passed in fops for ib_get_ucaps()
CVE-2026-53171 8.8 HIGH accel/ethosu: fix arithmetic issues in dma_length()

Showing top 20 of 146 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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