CVE-2026-35058 - blame None

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55ccc0	uddr	2026-04-22 20:58:00	1	# CVE-2026-35058 - fix server ASSERT() on receiving a suitably malformed packet with a valid tls-crypt-v2 key
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			3	tls-crypt-v2: Avoid interpreting opcode as part of WKc
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			5	The buffer we pass to tls_crypt_v2_extract_client_key contains the
			6	entire received control channel packet. We should skip the opcode before
			7	trying to read WKC.
			8
			9	This logic error is a second bug behind the XlabAI finding, next too the
			10	too-strict ASSERT in tls_crypt_unwrap.
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			12	Also remove a too strict ASSERT in tls_crypt_unwrap. We already check
			13	a few lines later for a too short packet and return a proper error
			14	("packet too short").
			15
			16	XlabAI found a way of triggering this ASSERT that requires a tls-crypt-v2
			17	client key that has a specific property (a specific byte need to have a
			18	specific value, about 1/256 probability). If an attacker can get hold of
			19	such a tls-crypt-v2 client key or observe a handshake using such a key,
			20	the attacker can trigger the ASSERT, crashing the server. Setups that do
			21	not use tls-crypt-v2 are not affected.
			22
			23	Independently, Cisco Talos reported a way to trigger this ASSERT with any
			24	tls-crypt-v2 key but this requires the attacker to be also in possession
			25	of the private key part of the tls-crypt-v2 client key or to inject packet
			26	into a live session of a client session.
			27
			28	OpenVPN version 2.6.0 through 2.6.19 and 2.7_alpha1 through 2.7.1 are affected. This is fixed in version 2.6.20 and 2.7.2.
			29
			30	CVE Record: [CVE-2026-35058](https://www.cve.org/CVERecord?id=CVE-2026-35058)
			31
			32	Github: [OpenVPN/openvpn-private-issues#111](https://github.com/OpenVPN/openvpn-private-issues/issues/111)
			33
			34	Release notes: [openvpn-2.7.2](https://community.openvpn.net/ReleaseHistory#openvpn-272-released-22-april-2026) [openvpn-2.6.20](https://community.openvpn.net/ReleaseHistory#openvpn-2620-released-22-april-2026)
			35
			36	Reported-By: XlabAI Team of Tencent Xuanwu Lab (xlabai@tencent.com)
39b66e	uddr	2026-04-22 20:58:38	37
55ccc0	uddr	2026-04-22 20:58:00	38	Reported-By: Guannan Wang (wgnbuaa@gmail.com
39b66e	uddr	2026-04-22 20:58:38	39
55ccc0	uddr	2026-04-22 20:58:00	40	Reported-By: Zhanpeng Liu (pkugenuine@gmail.com)
39b66e	uddr	2026-04-22 20:58:38	41
55ccc0	uddr	2026-04-22 20:58:00	42	Reported-By: Guancheng Li (lgcpku@gmail.com)
39b66e	uddr	2026-04-22 20:58:38	43
55ccc0	uddr	2026-04-22 20:58:00	44	Reported-By: Emma Reuter of Cisco ASIG (TALOS-2026-2381)