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TencentOS Server 2: kernel (TSSA-2026:1156)

medium Nessus Plugin ID 365153

Synopsis

The remote TencentOS Server 2 host is missing one or more security updates.

Description

The version of Tencent Linux installed on the remote TencentOS Server 2 host is prior to tested version. It is, therefore, affected by multiple vulnerabilities as referenced in the TSSA-2026:1156 advisory.

 Package updates are available for TencentOS Server 2 that fix the following vulnerabilities:

 CVE-2026-46331:
 In the Linux kernel, the following vulnerability has been resolved:

 net/sched: fix pedit partial COW leading to page cache corruption

 tcf_pedit_act() computes the COW range for skb_ensure_writable() once before the key loop using tcfp_off_max_hint, but the hint does not account for the runtime header offset added by typed keys. This can leave part of the write region un-COW'd.

 Fix by moving skb_ensure_writable() inside the per-key loop where the actual write offset is known, and add overflow checking on the offset arithmetic. For negative offsets (e.g. Ethernet header edits at ingress), use skb_cow() to COW the headroom instead. Guard offset_valid() against INT_MIN, where negation is undefined.

 CVE-2026-53212:
 In the Linux kernel, the following vulnerability has been resolved:

 netfilter: nft_tunnel: fix use-after-free on object destroy

 nft_tunnel_obj_destroy() calls metadata_dst_free() which directly kfree()s the metadata_dst, ignoring the dst_entry refcount. Packets that took a reference via dst_hold() in nft_tunnel_obj_eval() and are still queued (e.g. in a netem qdisc) are left with a dangling pointer. When these packets are eventually dequeued, dst_release() operates on freed memory.

 Replace metadata_dst_free() with dst_release() so the metadata_dst is freed only after all references are dropped. The dst subsystem already handles metadata_dst cleanup in dst_destroy() when DST_METADATA is set.

 CVE-2026-53266:
 In the Linux kernel, the following vulnerability has been resolved:

 netfilter: bridge: make ebt_snat ARP rewrite writable

 The ebtables SNAT target keeps the Ethernet source address rewrite behind skb_ensure_writable(skb, 0). This is intentional: at the bridge ebtables hooks the Ethernet header is addressed through skb_mac_header()/eth_hdr(), while skb->data points at the Ethernet payload. Asking skb_ensure_writable() for ETH_HLEN bytes would check the payload, not the Ethernet header, and would reintroduce the small packet regression fixed by commit 63137bc5882a.

 However, the optional ARP sender hardware address rewrite is different.
 It writes through skb_store_bits() at an offset relative to skb->data:

 skb_store_bits(skb, sizeof(struct arphdr), info->mac, ETH_ALEN)

 skb_header_pointer() only safely reads the ARP header; it does not make the later sender hardware address range writable. If that range is still held in a nonlinear skb fragment backed by a splice-imported file page, skb_store_bits() maps the frag page and copies the new MAC address directly into it.

 Ensure the ARP SHA range is writable before reading the ARP header and before calling skb_store_bits().

 CVE-2025-39964:
 In the Linux kernel, the following vulnerability has been resolved:

 crypto: af_alg - Disallow concurrent writes in af_alg_sendmsg

 Issuing two writes to the same af_alg socket is bogus as the data will be interleaved in an unpredictable fashion. Furthermore, concurrent writes may create inconsistencies in the internal socket state.

 Disallow this by adding a new ctx->write field that indiciates exclusive ownership for writing.

Tenable has extracted the preceding description block directly from the Tencent Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Solution

Update the affected packages.

See Also

https://mirrors.tencent.com/tlinux/errata/tssa-20261156.xml

Plugin Details

Severity: Medium

ID: 365153

File Name: tencentos_TSSA_2026_1156.nasl

Version: 1.2

Type: Local

Published: 10/12/2026

Updated: 10/13/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Critical

Score: 9.3

Percentile: 99.82

CVSS v2

Risk Factor: Medium

Base Score: 4.6

Temporal Score: 3.8

Vector: CVSS2#AV:L/AC:L/Au:S/C:N/I:N/A:C

CVSS Score Source: CVE-2025-39964

CVSS v3

Risk Factor: Medium

Base Score: 5.5

Temporal Score: 5.1

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Temporal Vector: CVSS:3.0/E:F/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:tencent:tencentos_server:2, p-cpe:/a:tencent:tencentos_server:kernel

Required KB Items: Host/local_checks_enabled, Host/cpu, Host/etc/os-release, Host/TencentOS/rpm-list

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 10/10/2026

Vulnerability Publication Date: 10/10/2025

CISA Known Exploited Vulnerability Due Dates: 9/21/2026

Exploitable With

Core Impact

Reference Information

CVE: CVE-2025-39964, CVE-2026-46331, CVE-2026-53212, CVE-2026-53266