CVE-2025-37953

  1. OpenCVE
  2. Vulnerabilities (CVE)
  3. CVE-2025-37953
In the Linux kernel, the following vulnerability has been resolved: sch_htb: make htb_deactivate() idempotent Alan reported a NULL pointer dereference in htb_next_rb_node() after we made htb_qlen_notify() idempotent. It turns out in the following case it introduced some regression: htb_dequeue_tree(): |-> fq_codel_dequeue() |-> qdisc_tree_reduce_backlog() |-> htb_qlen_notify() |-> htb_deactivate() |-> htb_next_rb_node() |-> htb_deactivate() For htb_next_rb_node(), after calling the 1st htb_deactivate(), the clprio[prio]->ptr could be already set to NULL, which means htb_next_rb_node() is vulnerable here. For htb_deactivate(), although we checked qlen before calling it, in case of qlen==0 after qdisc_tree_reduce_backlog(), we may call it again which triggers the warning inside. To fix the issues here, we need to: 1) Make htb_deactivate() idempotent, that is, simply return if we already call it before. 2) Make htb_next_rb_node() safe against ptr==NULL. Many thanks to Alan for testing and for the reproducer.

5.5 /10

CVSS v3 : MEDIUM

V3 Legend

Vector :

Exploitability : 1.8 / Impact : 3.6

Attack Vector LOCAL

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References
Link Resource
https://git.kernel.org/stable/c/31ff70ad39485698cf779f2078132d80b57f6c07 Patch
https://git.kernel.org/stable/c/3769478610135e82b262640252d90f6efb05be71 Patch
https://git.kernel.org/stable/c/98cd7ed92753090a714f0802d4434314526fe61d Patch
https://git.kernel.org/stable/c/99ff8a20fd61315bf9ae627440a5ff07d22ee153 Patch
https://git.kernel.org/stable/c/a9945f7cf1709adc5d2d31cb6cfc85627ce299a8 Patch
https://git.kernel.org/stable/c/c2d25fddd867ce20a266806634eeeb5c30cb520c Patch
https://git.kernel.org/stable/c/c4792b9e38d2f61b07eac72f10909fa76130314b Patch
https://git.kernel.org/stable/c/c928dd4f6bf0c25c72b11824a1e9ac9bd37296a0 Patch
https://lists.debian.org/debian-lts-announce/2025/08/msg00010.html Third Party Advisory
Configurations

Configuration 1 (hide)

OR cpe:2.3:o:linux:linux_kernel:6.1.138:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.6.90:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.12.28:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.14.6:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.15:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.15:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.15:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.15:rc5:*:*:*:*:*:*

Configuration 2 (hide)

cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
History

17 Dec 2025, 20:04

Type Values Removed Values Added
CPE cpe:2.3:o:linux:linux_kernel:6.15:rc5:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.15:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.1.138:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.15:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.6.90:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.15:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.12.28:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.14.6:*:*:*:*:*:*:*
CWE CWE-476
CVSS v2 : unknown
v3 : unknown 		v2 : unknown
v3 : 5.5
First Time Linux
Debian
Debian debian Linux
Linux linux Kernel
References () https://git.kernel.org/stable/c/31ff70ad39485698cf779f2078132d80b57f6c07 - () https://git.kernel.org/stable/c/31ff70ad39485698cf779f2078132d80b57f6c07 - Patch
References () https://git.kernel.org/stable/c/3769478610135e82b262640252d90f6efb05be71 - () https://git.kernel.org/stable/c/3769478610135e82b262640252d90f6efb05be71 - Patch
References () https://git.kernel.org/stable/c/98cd7ed92753090a714f0802d4434314526fe61d - () https://git.kernel.org/stable/c/98cd7ed92753090a714f0802d4434314526fe61d - Patch
References () https://git.kernel.org/stable/c/99ff8a20fd61315bf9ae627440a5ff07d22ee153 - () https://git.kernel.org/stable/c/99ff8a20fd61315bf9ae627440a5ff07d22ee153 - Patch
References () https://git.kernel.org/stable/c/a9945f7cf1709adc5d2d31cb6cfc85627ce299a8 - () https://git.kernel.org/stable/c/a9945f7cf1709adc5d2d31cb6cfc85627ce299a8 - Patch
References () https://git.kernel.org/stable/c/c2d25fddd867ce20a266806634eeeb5c30cb520c - () https://git.kernel.org/stable/c/c2d25fddd867ce20a266806634eeeb5c30cb520c - Patch
References () https://git.kernel.org/stable/c/c4792b9e38d2f61b07eac72f10909fa76130314b - () https://git.kernel.org/stable/c/c4792b9e38d2f61b07eac72f10909fa76130314b - Patch
References () https://git.kernel.org/stable/c/c928dd4f6bf0c25c72b11824a1e9ac9bd37296a0 - () https://git.kernel.org/stable/c/c928dd4f6bf0c25c72b11824a1e9ac9bd37296a0 - Patch
References () https://lists.debian.org/debian-lts-announce/2025/08/msg00010.html - () https://lists.debian.org/debian-lts-announce/2025/08/msg00010.html - Third Party Advisory

03 Nov 2025, 20:18

Type Values Removed Values Added
References
  • () https://lists.debian.org/debian-lts-announce/2025/08/msg00010.html -

28 Aug 2025, 15:15

Type Values Removed Values Added
References
  • () https://git.kernel.org/stable/c/a9945f7cf1709adc5d2d31cb6cfc85627ce299a8 -
  • () https://git.kernel.org/stable/c/c2d25fddd867ce20a266806634eeeb5c30cb520c -

04 Jun 2025, 13:15

Type Values Removed Values Added
References
  • () https://git.kernel.org/stable/c/99ff8a20fd61315bf9ae627440a5ff07d22ee153 -
Summary
  • (es) En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: sch_htb: hacer que htb_deactivate() sea idempotente. Alan informó una desreferencia de puntero NULL en htb_next_rb_node() después de que htb_qlen_notify() fuera idempotente. Resulta que en el siguiente caso introdujo alguna regresión: htb_dequeue_tree(): |-> fq_codel_dequeue() |-> qdisc_tree_reduce_backlog() |-> htb_qlen_notify() |-> htb_deactivate() |-> htb_next_rb_node() |-> htb_deactivate() Para htb_next_rb_node(), después de llamar al primer htb_deactivate(), el clprio[prio]->ptr podría estar ya establecido en NULL, lo que significa que htb_next_rb_node() es vulnerable aquí. Para htb_deactivate(), aunque verificamos qlen antes de llamarlo, en caso de qlen==0 después de qdisc_tree_reduce_backlog(), podemos llamarlo nuevamente, lo que activa la advertencia interna. Para solucionar estos problemas, necesitamos: 1) Hacer que htb_deactivate() sea idempotente, es decir, que simplemente regrese si ya lo llamamos. 2) Hacer que htb_next_rb_node() sea seguro contra ptr==NULL. Muchas gracias a Alan por las pruebas y por el reproductor.

20 May 2025, 16:15

Type Values Removed Values Added
New CVE
Information

Published : 2025-05-20 16:15

Updated : 2025-12-17 20:04

NVD link : CVE-2025-37953

Mitre link : CVE-2025-37953

CVE.ORG link : CVE-2025-37953

JSON object : View

Products Affected

debian

  • debian_linux

linux

  • linux_kernel
CWE
CWE-476

NULL Pointer Dereference