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AlmaLinux 9.2 [TuxCare] 安全更新：bpftool / kernel / kernel-abi-stablelists / kernel-core / 等多个漏洞 （ALMALINUX9.2：CLSA-2026：1778867412）

high Nessus 插件 ID 360766

语言：

简介

AlmaLinux 主机缺少一个或多个安全更新。

描述

AlmaLinux 9.2 主机上存在安装的程序包，该程序包受到 TuxCare ALMALINUX9.2：CLSA-2026：1778867412公告中提及的多个漏洞的影响。

 - 已修复 Linux 内核中的下列漏洞：net: skbuff: propagate shared-frag marker through frag-transfer helpers Two frag-transfer helpers (__pskb_copy_fclone() and skb_shift()) fail to propagate the SKBFL_SHARED_FRAG bit in skb_shinfo()->flags when moving frags from source to destination. __pskb_copy_fclone() defers the rest of the shinfo metadata to skb_copy_header() after copying frag descriptors, but that helper only carries over gso_{size,segs, type} and never touches skb_shinfo()->flags; skb_shift() moves frag descriptors directly and leaves flags untouched. As a result, the destination skb keeps a reference to the same externally-owned or page-cache-backed pages while reporting skb_has_shared_frag() as false. The mismatch is harmful in any in-place writer that uses skb_has_shared_frag() to decide whether shared pages must be detoured through skb_cow_data(). ESP input is one such writer (esp4.c, esp6.c), and a single nft 'dup to <local>' rule -- or any other nf_dup_ipv4() / xt_TEE caller -- is enough to land a pskb_copy()'d skb in esp_input() with the marker stripped, letting an unprivileged user write into the page cache of a root-owned read-only file via authencesn-ESN stray writes. Set SKBFL_SHARED_FRAG on the destination whenever frag descriptors were actually moved from the source. skb_copy() and skb_copy_expand() share skb_copy_header() too but linearize all paged data into freshly allocated head storage and emerge with nr_frags == 0, so skb_has_shared_frag() returns false on its own; they need no change. The same omission exists in skb_gro_receive() and skb_gro_receive_list().
 The former moves the incoming skb's frag descriptors into the accumulator's last sub-skb via two paths (a direct frag-move loop and the head_frag + memcpy path); the latter chains the incoming skb whole onto p's frag_list. Downstream skb_segment() reads only skb_shinfo(p)->flags, and skb_segment_list() reuses each sub-skb's shinfo as the nskb -- both p and lp must carry the marker. The same omission also exists in tcp_clone_payload(), which builds an MTU probe skb by moving frag descriptors from skbs on sk_write_queue into a freshly allocated nskb. The helper falls into the same family and warrants the same fix for consistency; no TCP TX-side in-place writer is currently known to reach a user page through this gap, but a future consumer depending on the marker would regress silently. The same omission exists in skb_segment(): the per-iteration flag merge takes only head_skb's flag, and the inner switch that rebinds frag_skb to list_skb on head_skb-frags exhaustion does not fold the new frag_skb's flag into nskb. Fold frag_skb's flag at both sites so segments drawing frags from frag_list members carry the marker.
 (CVE-2026-43503)

 - 已修复 Linux 内核中的下列漏洞：net: skbuff: preserve shared-frag marker during coalescing skb_try_coalesce() can attach paged frags from @from to @to. If @from has SKBFL_SHARED_FRAG set, the resulting @to skb can contain the same externally-owned or page-cache-backed frags, but the shared-frag marker is currently lost. That breaks the invariant relied on by later in-place writers. In particular, ESP input checks skb_has_shared_frag() before deciding whether an uncloned nonlinear skb can skip skb_cow_data(). If TCP receive coalescing has moved shared frags into an unmarked skb, ESP can see skb_has_shared_frag() as false and decrypt in place over page-cache backed frags.
 Propagate SKBFL_SHARED_FRAG when skb_try_coalesce() transfers paged frags. The tailroom copy path does not need the marker because it copies bytes into @to's linear data rather than transferring frag descriptors.
 (CVE-2026-46300)

请注意，Nessus 尚未测试这些问题，而是只依据应用程序自我报告的版本号进行判断。

解决方案

根据 TuxCare 公告 ALMALINUX9.2：CLSA-2026：1778867412 中的指南更新受影响的程序包。

另见

https://cve.tuxcare.com/els/releases/CLSA-2026:1778867412

http://www.nessus.org/u?1161ef9d

插件详情

严重性: High

ID: 360766

文件名: tuxcare_alma_linux_9.2_CLSA-2026-1778867412.nasl

版本: 1.2

类型: Local

发布时间: 2026/10/1

最近更新时间: 2026/10/2

支持的传感器: Continuous Assessment, Nessus Agent, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus

风险信息

VPR

风险因素: Critical

分数: 9.5

百分位: 99.87

Vendor

Vendor Severity: Important

CVSS v2

风险因素: Medium

基本分数: 6.8

时间分数: 5.9

矢量: CVSS2#AV:L/AC:L/Au:S/C:C/I:C/A:C

CVSS 分数来源: CVE-2026-46300

CVSS v3

风险因素: High

基本分数: 7.8

时间分数: 7.5

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

时间矢量: CVSS:3.0/E:H/RL:O/RC:C

漏洞信息

必需的 KB 项: Host/OS/extended-third-party, Host/local_checks_enabled, Host/AlmaLinux/release, Host/AlmaLinux/rpm-list, Host/cpu

可利用: true

易利用性: Exploits are available

补丁发布日期: 2026/5/15

漏洞发布日期: 2026/5/13

可利用的方式

Core Impact

Metasploit (Sample Linux Priv Esc, DescriptionThis exploit module illustrates how a vulnerability could be exploitedin an linux command for priv esc.})

参考资料信息

CVE: CVE-2026-43503, CVE-2026-46300

CLSA: 2026:1778867412