Linux Kernel up to 6.16-rc2 calipso calipso_req_setattr/calipso_req_delattr reference count

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5.0$0-$5k0.00

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.16-rc2 and classified as critical. This impacts the function calipso_req_setattr/calipso_req_delattr of the component calipso. Such manipulation leads to reference count. This vulnerability is documented as CVE-2025-38181. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.16-rc2 and classified as critical. Affected by this issue is the function calipso_req_setattr/calipso_req_delattr of the component calipso. The manipulation with an unknown input leads to a reference count vulnerability. Using CWE to declare the problem leads to CWE-911. The product uses a reference count to manage a resource, but it does not update or incorrectly updates the reference count. Impacted is availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: calipso: Fix null-ptr-deref in calipso_req_{set,del}attr(). syzkaller reported a null-ptr-deref in sock_omalloc() while allocating a CALIPSO option. [0] The NULL is of struct sock, which was fetched by sk_to_full_sk() in calipso_req_setattr(). Since commit a1a5344ddbe8 ("tcp: avoid two atomic ops for syncookies"), reqsk->rsk_listener could be NULL when SYN Cookie is returned to its client, as hinted by the leading SYN Cookie log. Here are 3 options to fix the bug: 1) Return 0 in calipso_req_setattr() 2) Return an error in calipso_req_setattr() 3) Alaways set rsk_listener 1) is no go as it bypasses LSM, but 2) effectively disables SYN Cookie for CALIPSO. 3) is also no go as there have been many efforts to reduce atomic ops and make TCP robust against DDoS. See also commit 3b24d854cb35 ("tcp/dccp: do not touch listener sk_refcnt under synflood"). As of the blamed commit, SYN Cookie already did not need refcounting, and no one has stumbled on the bug for 9 years, so no CALIPSO user will care about SYN Cookie. Let's return an error in calipso_req_setattr() and calipso_req_delattr() in the SYN Cookie case. This can be reproduced by [1] on Fedora and now connect() of nc times out. [0]: TCP: request_sock_TCPv6: Possible SYN flooding on port [::]:20002. Sending cookies. Oops: general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] PREEMPT SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037] CPU: 3 UID: 0 PID: 12262 Comm: syz.1.2611 Not tainted 6.14.0 #2 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 RIP: 0010:read_pnet include/net/net_namespace.h:406 [inline] RIP: 0010:sock_net include/net/sock.h:655 [inline] RIP: 0010:sock_kmalloc+0x35/0x170 net/core/sock.c:2806 Code: 89 d5 41 54 55 89 f5 53 48 89 fb e8 25 e3 c6 fd e8 f0 91 e3 00 48 8d 7b 30 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 26 01 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b RSP: 0018:ffff88811af89038 EFLAGS: 00010216 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffff888105266400 RDX: 0000000000000006 RSI: ffff88800c890000 RDI: 0000000000000030 RBP: 0000000000000050 R08: 0000000000000000 R09: ffff88810526640e R10: ffffed1020a4cc81 R11: ffff88810526640f R12: 0000000000000000 R13: 0000000000000820 R14: ffff888105266400 R15: 0000000000000050 FS: 00007f0653a07640(0000) GS:ffff88811af80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f863ba096f4 CR3: 00000000163c0005 CR4: 0000000000770ef0 PKRU: 80000000 Call Trace: <IRQ> ipv6_renew_options+0x279/0x950 net/ipv6/exthdrs.c:1288 calipso_req_setattr+0x181/0x340 net/ipv6/calipso.c:1204 calipso_req_setattr+0x56/0x80 net/netlabel/netlabel_calipso.c:597 netlbl_req_setattr+0x18a/0x440 net/netlabel/netlabel_kapi.c:1249 selinux_netlbl_inet_conn_request+0x1fb/0x320 security/selinux/netlabel.c:342 selinux_inet_conn_request+0x1eb/0x2c0 security/selinux/hooks.c:5551 security_inet_conn_request+0x50/0xa0 security/security.c:4945 tcp_v6_route_req+0x22c/0x550 net/ipv6/tcp_ipv6.c:825 tcp_conn_request+0xec8/0x2b70 net/ipv4/tcp_input.c:7275 tcp_v6_conn_request+0x1e3/0x440 net/ipv6/tcp_ipv6.c:1328 tcp_rcv_state_process+0xafa/0x52b0 net/ipv4/tcp_input.c:6781 tcp_v6_do_rcv+0x8a6/0x1a40 net/ipv6/tcp_ipv6.c:1667 tcp_v6_rcv+0x505e/0x5b50 net/ipv6/tcp_ipv6.c:1904 ip6_protocol_deliver_rcu+0x17c/0x1da0 net/ipv6/ip6_input.c:436 ip6_input_finish+0x103/0x180 net/ipv6/ip6_input.c:480 NF_HOOK include/linux/netfilter.h:314 [inline] NF_HOOK include/linux/netfilter.h:308 [inline] ip6_input+0x13c/0x6b0 net/ipv6/ip6_input.c:491 dst_input include/net/dst.h:469 [inline] ip6_rcv_finish net/ipv6/ip6_input.c:79 [inline] ip6_rcv_finish+0xb6/0x490 net/ipv6/ip6_input.c:69 NF_HOOK include/linux/netfilter.h:314 [inline] NF_HOOK include/linux/netf ---truncated---

The advisory is available at git.kernel.org. This vulnerability is handled as CVE-2025-38181 since 04/16/2025. The exploitation is known to be difficult. Technical details are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 243301 (SUSE SLES15 Security Update : kernel (SUSE-SU-2025:02588-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.4.295, 5.10.239, 5.15.186, 6.1.142, 6.6.95, 6.12.35, 6.15.4 or 6.16-rc3 eliminates this vulnerability. Applying the patch 956f1499412ed0953f6a116df7fdb855e9f1fc66/f4ae0f61dd9a63329ecb49b1e6356139d43240b8/dc724bd34d56f5589f7587a091a8cda2386826c4/058dd4a370f23a5553a9449f2db53d5bfa88d45e/bde8833eb075ba8e8674de88e32de6b669966451/988edde4d52d5c02ea4dd95d7619372a5e2fb7b7/d092c7fd8e220b23d6c47e03d7d0cc79e731f379/10876da918fa1aec0227fb4c67647513447f53a9 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 (243301), EUVD (EUVD-2025-20075) and CERT Bund (WID-SEC-2025-1465). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Affected

  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • IBM QRadar SIEM
  • SUSE openSUSE
  • RESF Rocky Linux
  • Dell Avamar
  • Open Source Linux Kernel
  • Dell NetWorker
  • Dell Secure Connect Gateway

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.1
VulDB Meta Temp Score: 5.0

VulDB Base Score: 4.8
VulDB Temp Score: 4.6
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: Reference count
CWE: CWE-911 / CWE-664
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: 243301
Nessus Name: SUSE SLES15 Security Update : kernel (SUSE-SU-2025:02588-1)

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.4.295/5.10.239/5.15.186/6.1.142/6.6.95/6.12.35/6.15.4/6.16-rc3
Patch: 956f1499412ed0953f6a116df7fdb855e9f1fc66/f4ae0f61dd9a63329ecb49b1e6356139d43240b8/dc724bd34d56f5589f7587a091a8cda2386826c4/058dd4a370f23a5553a9449f2db53d5bfa88d45e/bde8833eb075ba8e8674de88e32de6b669966451/988edde4d52d5c02ea4dd95d7619372a5e2fb7b7/d092c7fd8e220b23d6c47e03d7d0cc79e731f379/10876da918fa1aec0227fb4c67647513447f53a9

Timelineinfo

04/16/2025 CVE reserved
07/04/2025 +79 days Advisory disclosed
07/04/2025 +0 days VulDB entry created
12/19/2025 +168 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-38181 (🔒)
GCVE (CVE): GCVE-0-2025-38181
GCVE (VulDB): GCVE-100-314906
EUVD: 🔒
CERT Bund: WID-SEC-2025-1465 - Linux Kernel: Mehrere Schwachstellen erm&ouml;glichen Denial of Service

Entryinfo

Created: 07/04/2025 16:17
Updated: 12/19/2025 03:25
Changes: 07/04/2025 16:17 (59), 07/04/2025 21:27 (1), 07/20/2025 17:39 (7), 08/02/2025 10:45 (2), 08/25/2025 14:20 (1), 09/02/2025 11:25 (1), 09/10/2025 16:16 (1), 09/20/2025 23:07 (1), 11/02/2025 23:42 (1), 12/08/2025 02:05 (1), 12/19/2025 03:25 (13)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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