Linux Kernel up to 6.18.45/7.1.9 Tap tap_get_user_xdp uninitialized pointer

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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9.5$0-$5k0.82

Summaryinfo

A vulnerability identified as very critical has been detected in Linux Kernel up to 6.18.45/7.1.9. This affects the function tap_get_user_xdp of the component Tap. This manipulation causes uninitialized pointer. This vulnerability is handled as CVE-2026-80905. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.18.45/7.1.9. It has been declared as very critical. Affected by this vulnerability is the function tap_get_user_xdp of the component Tap. The manipulation with an unknown input leads to a uninitialized pointer vulnerability. The CWE definition for the vulnerability is CWE-824. The product accesses or uses a pointer that has not been initialized. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: net: tap: fix wrong transport_header when sending VLAN-tagged frame In tap_get_user_xdp(), when processing a VLAN-tagged frame (e.g. ETH_P_8021Q), skb_set_network_header() is called first to advance network_header past the VLAN tag to the inner protocol header. skb_probe_transport_header() is then called with skb->protocol still set to ETH_P_8021Q, while nhoff (derived from skb_network_offset()) already points past the VLAN tag to the inner protocol header. In __skb_flow_dissect(), proto is initialized to ETH_P_8021Q and nhoff points past the VLAN tag. When the dissector hits case ETH_P_8021Q, it reads a struct vlan_hdr at the current nhoff via __skb_header_pointer(), but that offset contains the inner protocol header (e.g. an IP header). The bytes are misinterpreted as a VLAN header, yielding a garbage encapsulated EtherType that matches no known protocol. The dissector returns false, so skb_probe_transport_header() never calls skb_set_transport_header(), leaving transport_header at its uninitialized sentinel value (~0U). Move skb_set_network_header() to after skb_probe_transport_header(). At the time skb_probe_transport_header() is called, network_header still points to the VLAN header (offset ETH_HLEN), so nhoff is correct and the flow dissector can parse the VLAN header, extract the inner EtherType, and advance nhoff to the inner protocol header, allowing transport_header to be set correctly.

The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2026-80905 since 08/26/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 09/04/2026).

Upgrading to version 6.18.46 or 7.1.10 eliminates this vulnerability. Applying the patch 5ffaa5d7f56ab24a8e23cf131eadfef31a3bbc4b/88b79ac89ecc04d7f2613f7e1c0b46f0c4ddb2f3/cbb35cbe8db268fefe34c23df15348cf99025298 is able to eliminate this problem.

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Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 10.0
VulDB Meta Temp Score: 9.5

VulDB Base Score: 10.0
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Uninitialized pointer
CWE: CWE-824 / CWE-908
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

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

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Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.18.46/7.1.10
Patch: 5ffaa5d7f56ab24a8e23cf131eadfef31a3bbc4b/88b79ac89ecc04d7f2613f7e1c0b46f0c4ddb2f3/cbb35cbe8db268fefe34c23df15348cf99025298

Timelineinfo

08/26/2026 CVE reserved
09/04/2026 +9 days Advisory disclosed
09/04/2026 +0 days VulDB entry created
09/04/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-80905 (🔒)
GCVE (CVE): GCVE-0-2026-80905
GCVE (VulDB): GCVE-100-399121

Entryinfo

Created: 09/04/2026 19:49
Changes: 09/04/2026 19:49 (59)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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