CVE-2026-45929 (GCVE-0-2026-45929)

Vulnerability from cvelistv5 – Published: 2026-05-27 12:17 – Updated: 2026-08-05 12:28
VLAI
Title
ovpn: fix possible use-after-free in ovpn_net_xmit
Summary
In the Linux kernel, the following vulnerability has been resolved: ovpn: fix possible use-after-free in ovpn_net_xmit When building the skb_list in ovpn_net_xmit, skb_share_check will free the original skb if it is shared. The current implementation continues to use the stale skb pointer for subsequent operations: - peer lookup, - skb_dst_drop (even though all segments produced by skb_gso_segment will have a dst attached), - ovpn_peer_stats_increment_tx. Fix this by moving the peer lookup and skb_dst_drop before segmentation so that the original skb is still valid when used. Return early if all segments fail skb_share_check and the list ends up empty. Also switch ovpn_peer_stats_increment_tx to use skb_list.next; the next patch fixes the stats logic.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7018 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 08857b5ec5d91d83e69e40a36554a8c7557b7301 , < 3e4fbcb4e078915367ba5576cd70d76dbc970f95 (git)
Affected: 08857b5ec5d91d83e69e40a36554a8c7557b7301 , < 442915c96a9bff1c7080e2aedabb1c03faa28d81 (git)
Affected: 08857b5ec5d91d83e69e40a36554a8c7557b7301 , < a5ec7baa44ea3a1d6aa0ca31c0ad82edf9affe41 (git)
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Linux Linux Affected: 6.16
Unaffected: 0 , < 6.16 (semver)
Unaffected: 6.18.14 , ≤ 6.18.* (semver)
Unaffected: 6.19.4 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)
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              "value": "AV:L - The vulnerable code is `ovpn_net_xmit`, the netdevice TX path (ndo_start_xmit), triggered by transmitting a packet out the local ovpn tunnel interface; the triggering precondition (a shared skb) is a local TX-side artifact and cannot be induced by a remote peer, whose data flows through the separate RX path.\nAC:L - The attacker controls both sides \u2014 arranging the skb-sharing reference holder and initiating the transmit \u2014 so the use-after-free race is within their control; choosing the higher-severity value where exploitation reliability is uncertain.\nPR:L - Creating an ovpn device and establishing the shared-skb condition requires CAP_NET_ADMIN/CAP_NET_RAW, which an unprivileged user can obtain inside a user namespace (unshare -Urn), so this is Low rather than High.\nUI:N - The bug is triggered purely by transmitting packets through the interface; no victim action is required.\nS:U - The use-after-free is contained within the kernel\u0027s own security authority and does not cross into a different security scope such as a VM or IOMMU boundary.\nC:H - A use-after-free read of the freed skb (protocol, data, len) lets an attacker who controls the reclaimed object contents read sensitive kernel memory.\nI:H - The use-after-free can be leveraged via heap grooming of the freed skb to corrupt kernel state and achieve write/control-flow primitives.\nA:H - Dereferencing the freed skb readily causes a kernel oops/panic, a full denial of service."
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}



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