CVE-2026-80800

nfc: llcp: bound the connect_sn TLV walk to the skb

Published Sep 4, 2026 CVSS n/a EPSS < 1% KEV · Not listed

Description

In the Linux kernel, the following vulnerability has been resolved:

nfc: llcp: bound the connect_sn TLV walk to the skb

Commit 27256cdb290e ("nfc: llcp: bound SNL TLV parsing to the skb and
add length checks") fixed the unbounded TLV walk in nfc_llcp_recv_snl(),
and commit d8bd2dedbde5 ("nfc: llcp: fix OOB read and u8 offset wrap in
TLV parsers") subsequently bounded nfc_llcp_parse_gb_tlv() and
nfc_llcp_parse_connection_tlv(). One sibling parser sharing the same
pattern remains unbounded: nfc_llcp_connect_sn().

nfc_llcp_connect_sn() walks a TLV list, reading a two-byte header
(type, length) followed by length bytes of value, without checking that
the two header bytes or the declared length stay within the buffer. It
returns a pointer to a service name of up to 255 bytes that may point
past the end of the skb; it is subsequently consumed by memcmp() in
nfc_llcp_sock_from_sn(). In addition tlv_array_len was computed as
"skb->len - LLCP_HEADER_SIZE" in size_t, so a CONNECT/CC frame shorter
than the LLCP header underflows to a huge length and the walk runs far
past the buffer.

nfc_llcp_connect_sn() is reachable from nfc_llcp_recv_connect() and
nfc_llcp_recv_cc(), i.e. from received CONNECT and CC PDUs. A nearby
NFC device can reach this without authentication; LLCP link activation
happens automatically after NFC-DEP, and the nfc_llcp_rx_skb()
dispatcher applies no minimum-length guard.

Walk the TLV list by pointer, bounded by skb_tail_pointer(skb), and
validate each declared length before use, matching the approach already
used for nfc_llcp_recv_snl(). Starting the walk at
&skb->data[LLCP_HEADER_SIZE] against the tail pointer also removes the
size_t underflow for short frames.

Found by 0sec automated security-research tooling (https://0sec.ai).

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Linux

unaffected

Version	Status	Constraints
`d646960f7986fefb460a2b062d5ccc8ccfeacc3a`	affected	< b2ebdfe3d5b76e91f267a61cbc3f9a0e3f77071e
`d646960f7986fefb460a2b062d5ccc8ccfeacc3a`	affected	< e18d044bab6d3d0280639098c3fe6621692cbfe2
`d646960f7986fefb460a2b062d5ccc8ccfeacc3a`	affected	< 65a0ec7783b06068dda6745dd689bf4a91ee64aa
`d646960f7986fefb460a2b062d5ccc8ccfeacc3a`	affected	< 1964addc8dd535a05d5d3b55b4d1ac19ae31aa65
`d646960f7986fefb460a2b062d5ccc8ccfeacc3a`	affected	< 389986fd79e4d43f971a03b512645a1bb63c982f
`d646960f7986fefb460a2b062d5ccc8ccfeacc3a`	affected	< e87527b506c40db9af528714b7b1240918eb80fc
`d646960f7986fefb460a2b062d5ccc8ccfeacc3a`	affected	< 22e5177ba1196a0b272a6a46c2575eb940a939c4
`d646960f7986fefb460a2b062d5ccc8ccfeacc3a`	affected	< 0cfbdb0e13ab5b0765d77f96af67eb879cbc9736
`d646960f7986fefb460a2b062d5ccc8ccfeacc3a`	affected	< 55c68ac93e7dacc0f5f608b9c39dd4ff48cf28e8

Linux

affected

Version	Status	Constraints
`3.3`	affected	—
`0`	unaffected	< 3.3
`5.10.267`	unaffected	≤ 5.10.*
`5.15.218`	unaffected	≤ 5.15.*
`6.1.185`	unaffected	≤ 6.1.*
`6.6.154`	unaffected	≤ 6.6.*
`6.12.106`	unaffected	≤ 6.12.*
`6.18.47`	unaffected	≤ 6.18.*
`7.1.11`	unaffected	≤ 7.1.*
`7.2.1`	unaffected	≤ 7.2.*
`7.3`	unaffected	≤ *

No data.

Vendor Product Versions

Linux

Linux Kernel

Version	Status	Scheme	Platform
`[d646960f7986fefb460a2b062d5ccc8ccfeacc3a,b2ebdfe3d5b76e91f267a61cbc3f9a0e3f77071e)`	affected	code_commit	—
`[d646960f7986fefb460a2b062d5ccc8ccfeacc3a,e18d044bab6d3d0280639098c3fe6621692cbfe2)`	affected	code_commit	—
`[d646960f7986fefb460a2b062d5ccc8ccfeacc3a,65a0ec7783b06068dda6745dd689bf4a91ee64aa)`	affected	code_commit	—
`[d646960f7986fefb460a2b062d5ccc8ccfeacc3a,1964addc8dd535a05d5d3b55b4d1ac19ae31aa65)`	affected	code_commit	—
`[d646960f7986fefb460a2b062d5ccc8ccfeacc3a,389986fd79e4d43f971a03b512645a1bb63c982f)`	affected	code_commit	—
`[d646960f7986fefb460a2b062d5ccc8ccfeacc3a,e87527b506c40db9af528714b7b1240918eb80fc)`	affected	code_commit	—
`[d646960f7986fefb460a2b062d5ccc8ccfeacc3a,22e5177ba1196a0b272a6a46c2575eb940a939c4)`	affected	code_commit	—
`[d646960f7986fefb460a2b062d5ccc8ccfeacc3a,0cfbdb0e13ab5b0765d77f96af67eb879cbc9736)`	affected	code_commit	—
`[d646960f7986fefb460a2b062d5ccc8ccfeacc3a,55c68ac93e7dacc0f5f608b9c39dd4ff48cf28e8)`	affected	code_commit	—

Linux

Linux Kernel

Version	Status	Scheme	Platform
`3.3`	affected	generic	—
`[0,3.3)`	unaffected	generic	—
`[5.10.267,5.10.*]`	unaffected	generic	—
`[5.15.218,5.15.*]`	unaffected	generic	—
`[6.1.185,6.1.*]`	unaffected	generic	—
`[6.6.154,6.6.*]`	unaffected	generic	—
`[6.12.106,6.12.*]`	unaffected	generic	—
`[7.1.11,7.1.*]`	unaffected	generic	—
`[6.18.47,6.18.*]`	unaffected	generic	—
`[7.2.1,7.2.*]`	unaffected	generic	—
`[7.3-rc1,*]`	unaffected	generic	—

Remediation

No solution or workaround provided in the CVE record

Tracking

Advisories

Source	ID	Title
Debian DLA	DLA-4777-1	linux security update
Debian DLA	DLA-4788-1	linux-6.12 security update
Ubuntu USN	USN-8961-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9019-1	Linux kernel (Azure) vulnerabilities
Ubuntu USN	USN-9020-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9022-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9023-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9024-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9025-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9026-1	Linux kernel (Azure) vulnerabilities
Ubuntu USN	USN-9029-1	Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN	USN-9039-1	Linux kernel (Azure CVM) vulnerabilities
Ubuntu USN	USN-9040-1	Linux kernel (Low Latency NVIDIA) vulnerabilities
Ubuntu USN	USN-9066-1	Linux kernel (HWE) vulnerabilities
Ubuntu USN	USN-9091-1	Linux kernel (NVIDIA Tegra) vulnerabilities

Metrics

No CVSS v4.0

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.234% probability within 30 days)

Key SSVC decision points have not yet been added.

References

Link	Providers
https://git.kernel.org/stable/c/0cfbdb0e13ab5b0765d77f96af67eb879cbc9736
https://git.kernel.org/stable/c/1964addc8dd535a05d5d3b55b4d1ac19ae31aa65
https://git.kernel.org/stable/c/22e5177ba1196a0b272a6a46c2575eb940a939c4
https://git.kernel.org/stable/c/389986fd79e4d43f971a03b512645a1bb63c982f
https://git.kernel.org/stable/c/55c68ac93e7dacc0f5f608b9c39dd4ff48cf28e8
https://git.kernel.org/stable/c/65a0ec7783b06068dda6745dd689bf4a91ee64aa
https://git.kernel.org/stable/c/b2ebdfe3d5b76e91f267a61cbc3f9a0e3f77071e
https://git.kernel.org/stable/c/e18d044bab6d3d0280639098c3fe6621692cbfe2
https://git.kernel.org/stable/c/e87527b506c40db9af528714b7b1240918eb80fc

History

Sep 4, 2026 10:00 PM Weaknesses updated View changes

Type	Values Removed	Values Added
Weaknesses		CWE-125 CWE-20

Sep 4, 2026 3:30 PM Description updated. Title updated. First appearance in the feed. Affected versions updated. Affected vendors updated. Added references View changes

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: nfc: llcp: bound the connect_sn TLV walk to the skb Commit 27256cdb290e ("nfc: llcp: bound SNL TLV parsing to the skb and add length checks") fixed the unbounded TLV walk in nfc_llcp_recv_snl(), and commit d8bd2dedbde5 ("nfc: llcp: fix OOB read and u8 offset wrap in TLV parsers") subsequently bounded nfc_llcp_parse_gb_tlv() and nfc_llcp_parse_connection_tlv(). One sibling parser sharing the same pattern remains unbounded: nfc_llcp_connect_sn(). nfc_llcp_connect_sn() walks a TLV list, reading a two-byte header (type, length) followed by length bytes of value, without checking that the two header bytes or the declared length stay within the buffer. It returns a pointer to a service name of up to 255 bytes that may point past the end of the skb; it is subsequently consumed by memcmp() in nfc_llcp_sock_from_sn(). In addition tlv_array_len was computed as "skb->len - LLCP_HEADER_SIZE" in size_t, so a CONNECT/CC frame shorter than the LLCP header underflows to a huge length and the walk runs far past the buffer. nfc_llcp_connect_sn() is reachable from nfc_llcp_recv_connect() and nfc_llcp_recv_cc(), i.e. from received CONNECT and CC PDUs. A nearby NFC device can reach this without authentication; LLCP link activation happens automatically after NFC-DEP, and the nfc_llcp_rx_skb() dispatcher applies no minimum-length guard. Walk the TLV list by pointer, bounded by skb_tail_pointer(skb), and validate each declared length before use, matching the approach already used for nfc_llcp_recv_snl(). Starting the walk at &skb->data[LLCP_HEADER_SIZE] against the tail pointer also removes the size_t underflow for short frames. Found by 0sec automated security-research tooling (https://0sec.ai).
Title		nfc: llcp: bound the connect_sn TLV walk to the skb
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/0cfbdb0e13ab5b0765d77f96af67eb879cbc9736 https://git.kernel.org/stable/c/1964addc8dd535a05d5d3b55b4d1ac19ae31aa65 https://git.kernel.org/stable/c/22e5177ba1196a0b272a6a46c2575eb940a939c4 https://git.kernel.org/stable/c/389986fd79e4d43f971a03b512645a1bb63c982f https://git.kernel.org/stable/c/55c68ac93e7dacc0f5f608b9c39dd4ff48cf28e8 https://git.kernel.org/stable/c/65a0ec7783b06068dda6745dd689bf4a91ee64aa https://git.kernel.org/stable/c/b2ebdfe3d5b76e91f267a61cbc3f9a0e3f77071e https://git.kernel.org/stable/c/e18d044bab6d3d0280639098c3fe6621692cbfe2 https://git.kernel.org/stable/c/e87527b506c40db9af528714b7b1240918eb80fc