Linux Kernel up to 6.13.6 net/llc/llc_s_ac.c skb_get state issue

CVSS Meta Temp Score
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CTI Interest Score
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4.9$0-$5k0.00

Summaryinfo

A vulnerability classified as problematic has been found in Linux Kernel up to 6.13.6. Affected is the function skb_get of the file net/llc/llc_s_ac.c. The manipulation leads to state issue. This vulnerability is traded as CVE-2025-21925. There is no exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Linux Kernel up to 6.13.6. This issue affects the function skb_get of the file net/llc/llc_s_ac.c. The manipulation with an unknown input leads to a state issue vulnerability. Using CWE to declare the problem leads to CWE-371. The impact remains unknown. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: llc: do not use skb_get() before dev_queue_xmit() syzbot is able to crash hosts [1], using llc and devices not supporting IFF_TX_SKB_SHARING. In this case, e1000 driver calls eth_skb_pad(), while the skb is shared. Simply replace skb_get() by skb_clone() in net/llc/llc_s_ac.c Note that e1000 driver might have an issue with pktgen, because it does not clear IFF_TX_SKB_SHARING, this is an orthogonal change. We need to audit other skb_get() uses in net/llc. [1] kernel BUG at net/core/skbuff.c:2178 ! Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI CPU: 0 UID: 0 PID: 16371 Comm: syz.2.2764 Not tainted 6.14.0-rc4-syzkaller-00052-gac9c34d1e45a #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 RIP: 0010:pskb_expand_head+0x6ce/0x1240 net/core/skbuff.c:2178 Call Trace: <TASK> __skb_pad+0x18a/0x610 net/core/skbuff.c:2466 __skb_put_padto include/linux/skbuff.h:3843 [inline] skb_put_padto include/linux/skbuff.h:3862 [inline] eth_skb_pad include/linux/etherdevice.h:656 [inline] e1000_xmit_frame+0x2d99/0x5800 drivers/net/ethernet/intel/e1000/e1000_main.c:3128 __netdev_start_xmit include/linux/netdevice.h:5151 [inline] netdev_start_xmit include/linux/netdevice.h:5160 [inline] xmit_one net/core/dev.c:3806 [inline] dev_hard_start_xmit+0x9a/0x7b0 net/core/dev.c:3822 sch_direct_xmit+0x1ae/0xc30 net/sched/sch_generic.c:343 __dev_xmit_skb net/core/dev.c:4045 [inline] __dev_queue_xmit+0x13d4/0x43e0 net/core/dev.c:4621 dev_queue_xmit include/linux/netdevice.h:3313 [inline] llc_sap_action_send_test_c+0x268/0x320 net/llc/llc_s_ac.c:144 llc_exec_sap_trans_actions net/llc/llc_sap.c:153 [inline] llc_sap_next_state net/llc/llc_sap.c:182 [inline] llc_sap_state_process+0x239/0x510 net/llc/llc_sap.c:209 llc_ui_sendmsg+0xd0d/0x14e0 net/llc/af_llc.c:993 sock_sendmsg_nosec net/socket.c:718 [inline]

The advisory is shared at git.kernel.org. The identification of this vulnerability is CVE-2025-21925 since 12/29/2024. The exploitation is known to be difficult. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 02/01/2026).

The vulnerability scanner Nessus provides a plugin with the ID 234309 (Debian dsa-5900 : affs-modules-6.1.0-28-4kc-malta-di - security update), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.4.291, 5.10.235, 5.15.179, 6.1.131, 6.6.83, 6.12.19 or 6.13.7 eliminates this vulnerability. Applying the patch cd1c44327bbbd50fc24f2b38892f5f328b784d0f/13f3f872627f0f27c31245524fc11367756240ad/9b6f083db141ece0024be01526aa05aa978811cb/17f86e25431ebc15aa9245ff156414fdad47822d/416e8b4c20c6398044e93008deefd563289f477d/0f764208dc24ea043c3e20194d32aebf94f8459c/056e8a46d79e22983bae4267e0d9c52927076f46/64e6a754d33d31aa844b3ee66fb93ac84ca1565e is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (234309) and CERT Bund (WID-SEC-2025-0683). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

  • Google Container-Optimized OS
  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • RESF Rocky Linux
  • Dell Avamar
  • Open Source Linux Kernel
  • SolarWinds Security Event Manager
  • Dell NetWorker
  • Dell Secure Connect Gateway
  • IBM Security Verify Access

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.0
VulDB Meta Temp Score: 4.9

VulDB Base Score: 4.6
VulDB Temp Score: 4.4
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 5.5
NVD Vector: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

Exploitinginfo

Class: State issue
CWE: CWE-371
CAPEC: 🔍
ATT&CK: 🔍

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 234309
Nessus Name: Debian dsa-5900 : affs-modules-6.1.0-28-4kc-malta-di - security update

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: Kernel 5.4.291/5.10.235/5.15.179/6.1.131/6.6.83/6.12.19/6.13.7
Patch: cd1c44327bbbd50fc24f2b38892f5f328b784d0f/13f3f872627f0f27c31245524fc11367756240ad/9b6f083db141ece0024be01526aa05aa978811cb/17f86e25431ebc15aa9245ff156414fdad47822d/416e8b4c20c6398044e93008deefd563289f477d/0f764208dc24ea043c3e20194d32aebf94f8459c/056e8a46d79e22983bae4267e0d9c52927076f46/64e6a754d33d31aa844b3ee66fb93ac84ca1565e

Timelineinfo

12/29/2024 🔍
04/01/2025 +92 days 🔍
04/01/2025 +0 days 🔍
02/01/2026 +306 days 🔍

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-21925 (🔍)
GCVE (CVE): GCVE-0-2025-21925
GCVE (VulDB): GCVE-100-302609
CERT Bund: WID-SEC-2025-0683 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 04/01/2025 18:57
Updated: 02/01/2026 06:25
Changes: 04/01/2025 18:57 (58), 04/14/2025 13:56 (2), 07/20/2025 02:35 (7), 07/21/2025 18:30 (1), 10/26/2025 19:49 (1), 10/31/2025 21:30 (13), 02/01/2026 06:25 (1)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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