AlmaLinux 9.6 [TuxCare] 安全性更新：kernel / kernel-64k / kernel-64k-core / kernel-64k-debug / etc 多個弱點 （ALMALINUX9.6：CLSA-2026：1778930898）
high Nessus Plugin ID 351723
語言:
概要
AlmaLinux 主機缺少一個或多個安全性更新。說明
AlmaLinux 9.6 主機已安裝的套件會受到 TuxCare ALMALINUX9.6：CLSA-2026：1778930898 公告中提及的多個弱點影響。- 已解決 Linux 核心中的下列弱點：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)
- 已解決 Linux 核心中的下列弱點：ptrace: slightly saner 'get_dumpable()' logic The 'dumpability' of a task is fundamentally about the memory image of the task - the concept comes from whether it can core dump or not - and makes no sense when you don't have an associated mm. And almost all users do in fact use it only for the case where the task has a mm pointer.
But we have one odd special case: ptrace_may_access() uses 'dumpable' to check various other things entirely independently of the MM (typically explicitly using flags like PTRACE_MODE_READ_FSCREDS).
Including for threads that no longer have a VM (and maybe never did, like most kernel threads). It's not what this flag was designed for, but it is what it is. The ptrace code does check that the uid/gid matches, so you do have to be uid-0 to see kernel thread details, but this means that the traditional drop capabilities model doesn't make any difference for this all. Make it all make a *bit* more sense by saying that if you don't have a MM pointer, we'll use a cached last dumpability flag if the thread ever had a MM (it will be zero for kernel threads since it is never set), and require a proper CAP_SYS_PTRACE capability to override. (CVE-2026-46333)
請注意，Nessus 並未測試這些問題，而是僅依據應用程式自我報告的版本號碼作出判斷。
解決方案
根據 TuxCare 公告 ALMALINUX9.6：CLSA-2026：1778930898 中的指引更新受影響的套件。另請參閱
Plugin 詳細資訊
嚴重性: High
ID: 351723
檔案名稱: tuxcare_alma_linux_9.6_CLSA-2026-1778930898.nasl
版本: 1.5
類型: Local
已發布: 2026/9/30
已更新: 2026/10/22
支援的感應器: Nessus Agent, Continuous Assessment, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus
風險資訊
VPR
風險因素: Critical
分數: 9.2
百分位數: 99.77
Vendor
Vendor Severity: Important
CVSS v2
風險因素: Medium
基本分數: 6.8
時間性分數: 5.9
媒介: CVSS2#AV:L/AC:L/Au:S/C:C/I:C/A:C
CVSS 評分資料來源: CVE-2026-43503
CVSS v3
風險因素: High
基本分數: 7.8
時間性分數: 7.5
媒介: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
時間媒介: CVSS:3.0/E:H/RL:O/RC:C
CVSS 評分資料來源: CVE-2026-46333
弱點資訊
必要的 KB 項目: Host/local_checks_enabled, Host/cpu, Host/AlmaLinux/release, Host/AlmaLinux/rpm-list, Host/OS/extended-third-party
可被惡意程式利用: true
可輕鬆利用: Exploits are available
修補程式發佈日期: 2026/5/16
弱點發布日期: 2026/5/15
可惡意利用
Core Impact
Metasploit (Linux Kernel DirtyClone Local Privilege Escalation)
參考資訊
CVE: CVE-2026-43503, CVE-2026-46333
CLSA: 2026:1778930898