In the Linux kernel, the following vulnerability has been resolved: net: af_key: initialize alg_key_len for IPComp states pfkey_msg2xfrm_state()… (CVE-2026-64436)
In the Linux kernel, the following vulnerability has been resolved: net: af_key: initialize alg_key_len for IPComp states pfkey_msg2xfrm_state() handles the IPComp (SADB_X_SATYPE_IPCOMP) case by allocating x->calg and copying only the algorithm name: x->calg = kmalloc_obj(*x->calg); if (!x->calg) { err = -ENOMEM; goto out; } strcpy(x->calg->alg_name, a->name); x->props.calgo = sa->sadb_sa_encrypt; Unlike the authentication (x->aalg) and encryption (x->ealg) branches of the same function, the compression branch never initializes calg->alg_key_len. IPComp carries no key and the allocation only reserves sizeof(struct xfrm_algo) (i.e. no room for a key), so the field is left containing uninitialized slab data. calg->alg_key_len is later used as a length by xfrm_algo_clone() when an IPComp state is cloned during XFRM_MSG_MIGRATE: xfrm_state_migrate() xfrm_state_clone_and_setup() x->calg = xfrm_algo_clone(orig->calg); kmemdup(orig, xfrm_alg_len(orig)); where xfrm_alg_len() returns sizeof(*alg) + (alg_key_len + 7) / 8. With a non-zero garbage alg_key_len, kmemdup() reads past the end of the 68-byte calg object. Adding an IPComp SA via PF_KEY and then migrating it triggers (net-next, KASAN, init_on_alloc=0): BUG: KASAN: slab-out-of-bounds in kmemdup_noprof+0x44/0x60 Read of size 4164 at addr ff11000025a74980 by task diag2/9287 CPU: 3 UID: 0 PID: 9287 Comm: diag2 7.1.0-rc6-g903db046d557 #1 Call Trace: <TASK> dump_stack_lvl+0x10e/0x1f0 print_report+0xf7/0x600 kasan_report+0xe4/0x120 kasan_check_range+0x105/0x1b0 __asan_memcpy+0x23/0x60 kmemdup_noprof+0x44/0x60 xfrm_state_migrate+0x70a/0x1da0 xfrm_migrate+0x753/0x18a0 xfrm_do_migrate+0xb47/0xf10 xfrm_user_rcv_msg+0x411/0xb50 netlink_rcv_skb+0x158/0x420 xfrm_netlink_rcv+0x71/0x90 netlink_unicast+0x584/0x850 netlink_sendmsg+0x8b0/0xdc0 ____sys_sendmsg+0x9f7/0xb90 ___sys_sendmsg+0x134/0x1d0 __sys_sendmsg+0x16d/0x220 do_syscall_64+0x116/0x7d0 entry_SYSCALL_64_after_hwframe+0x77/0x7f </TASK> Allocated by task 9287: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 __kasan_kmalloc+0xaa/0xb0 pfkey_add+0x2652/0x2ea0 pfkey_process+0x6d0/0x830 pfkey_sendmsg+0x42c/0x850 __sys_sendto+0x461/0x4b0 __x64_sys_sendto+0xe0/0x1c0 do_syscall_64+0x116/0x7d0 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ff11000025a74980 which belongs to the cache kmalloc-96 of size 96 The buggy address is located 0 bytes inside of allocated 68-byte region [ff11000025a74980, ff11000025a749c4) Depending on the uninitialized value the same field can instead request an oversized kmemdup() allocation and make the migration clone fail. The XFRM netlink path is not affected: verify_one_alg() rejects an XFRMA_ALG_COMP attribute shorter than xfrm_alg_len(), so a calg added via XFRM_MSG_NEWSA is always self-consistent. Initialize calg->alg_key_len to 0, matching the aalg/ealg branches.
AI Analysis
Technical Summary
The Linux kernel's pfkey_msg2xfrm_state() function mishandles IPComp (SADB_X_SATYPE_IPCOMP) states by allocating the compression algorithm structure (calg) without initializing the alg_key_len field. Since IPComp carries no key, the allocated memory is smaller and alg_key_len remains uninitialized, containing garbage data. Later, during XFRM_MSG_MIGRATE operations, xfrm_algo_clone() uses alg_key_len to determine the size of memory to duplicate. If alg_key_len is non-zero garbage, kmemdup() reads beyond the allocated memory, causing slab-out-of-bounds errors detected by KASAN. This can lead to kernel memory corruption or crashes. The vulnerability does not affect the XFRM netlink path due to input validation. The fix initializes calg->alg_key_len to zero, aligning with other algorithm branches and preventing out-of-bounds access.
Potential Impact
The vulnerability can cause out-of-bounds memory reads in kernel space during migration of IPComp states, potentially leading to kernel crashes or memory corruption. This affects the stability and security of the kernel's networking subsystem handling IPComp. There is no indication of remote code execution or privilege escalation from the provided data. The issue is triggered by adding an IPComp Security Association via PF_KEY and migrating it.
Mitigation Recommendations
A fix is available that initializes the alg_key_len field to zero in the IPComp compression algorithm structure, preventing uninitialized memory usage. Users should update their Linux kernel to a version that includes this fix. Since this is a kernel vulnerability, applying the official kernel patch or upgrading to a fixed kernel release is the recommended remediation. Patch status is not explicitly stated in the input data; check the vendor advisory for the exact fixed kernel versions and apply updates accordingly.
In the Linux kernel, the following vulnerability has been resolved: net: af_key: initialize alg_key_len for IPComp states pfkey_msg2xfrm_state()… (CVE-2026-64436)
Description
In the Linux kernel, the following vulnerability has been resolved: net: af_key: initialize alg_key_len for IPComp states pfkey_msg2xfrm_state() handles the IPComp (SADB_X_SATYPE_IPCOMP) case by allocating x->calg and copying only the algorithm name: x->calg = kmalloc_obj(*x->calg); if (!x->calg) { err = -ENOMEM; goto out; } strcpy(x->calg->alg_name, a->name); x->props.calgo = sa->sadb_sa_encrypt; Unlike the authentication (x->aalg) and encryption (x->ealg) branches of the same function, the compression branch never initializes calg->alg_key_len. IPComp carries no key and the allocation only reserves sizeof(struct xfrm_algo) (i.e. no room for a key), so the field is left containing uninitialized slab data. calg->alg_key_len is later used as a length by xfrm_algo_clone() when an IPComp state is cloned during XFRM_MSG_MIGRATE: xfrm_state_migrate() xfrm_state_clone_and_setup() x->calg = xfrm_algo_clone(orig->calg); kmemdup(orig, xfrm_alg_len(orig)); where xfrm_alg_len() returns sizeof(*alg) + (alg_key_len + 7) / 8. With a non-zero garbage alg_key_len, kmemdup() reads past the end of the 68-byte calg object. Adding an IPComp SA via PF_KEY and then migrating it triggers (net-next, KASAN, init_on_alloc=0): BUG: KASAN: slab-out-of-bounds in kmemdup_noprof+0x44/0x60 Read of size 4164 at addr ff11000025a74980 by task diag2/9287 CPU: 3 UID: 0 PID: 9287 Comm: diag2 7.1.0-rc6-g903db046d557 #1 Call Trace: <TASK> dump_stack_lvl+0x10e/0x1f0 print_report+0xf7/0x600 kasan_report+0xe4/0x120 kasan_check_range+0x105/0x1b0 __asan_memcpy+0x23/0x60 kmemdup_noprof+0x44/0x60 xfrm_state_migrate+0x70a/0x1da0 xfrm_migrate+0x753/0x18a0 xfrm_do_migrate+0xb47/0xf10 xfrm_user_rcv_msg+0x411/0xb50 netlink_rcv_skb+0x158/0x420 xfrm_netlink_rcv+0x71/0x90 netlink_unicast+0x584/0x850 netlink_sendmsg+0x8b0/0xdc0 ____sys_sendmsg+0x9f7/0xb90 ___sys_sendmsg+0x134/0x1d0 __sys_sendmsg+0x16d/0x220 do_syscall_64+0x116/0x7d0 entry_SYSCALL_64_after_hwframe+0x77/0x7f </TASK> Allocated by task 9287: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 __kasan_kmalloc+0xaa/0xb0 pfkey_add+0x2652/0x2ea0 pfkey_process+0x6d0/0x830 pfkey_sendmsg+0x42c/0x850 __sys_sendto+0x461/0x4b0 __x64_sys_sendto+0xe0/0x1c0 do_syscall_64+0x116/0x7d0 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ff11000025a74980 which belongs to the cache kmalloc-96 of size 96 The buggy address is located 0 bytes inside of allocated 68-byte region [ff11000025a74980, ff11000025a749c4) Depending on the uninitialized value the same field can instead request an oversized kmemdup() allocation and make the migration clone fail. The XFRM netlink path is not affected: verify_one_alg() rejects an XFRMA_ALG_COMP attribute shorter than xfrm_alg_len(), so a calg added via XFRM_MSG_NEWSA is always self-consistent. Initialize calg->alg_key_len to 0, matching the aalg/ealg branches.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Linux kernel's pfkey_msg2xfrm_state() function mishandles IPComp (SADB_X_SATYPE_IPCOMP) states by allocating the compression algorithm structure (calg) without initializing the alg_key_len field. Since IPComp carries no key, the allocated memory is smaller and alg_key_len remains uninitialized, containing garbage data. Later, during XFRM_MSG_MIGRATE operations, xfrm_algo_clone() uses alg_key_len to determine the size of memory to duplicate. If alg_key_len is non-zero garbage, kmemdup() reads beyond the allocated memory, causing slab-out-of-bounds errors detected by KASAN. This can lead to kernel memory corruption or crashes. The vulnerability does not affect the XFRM netlink path due to input validation. The fix initializes calg->alg_key_len to zero, aligning with other algorithm branches and preventing out-of-bounds access.
Potential Impact
The vulnerability can cause out-of-bounds memory reads in kernel space during migration of IPComp states, potentially leading to kernel crashes or memory corruption. This affects the stability and security of the kernel's networking subsystem handling IPComp. There is no indication of remote code execution or privilege escalation from the provided data. The issue is triggered by adding an IPComp Security Association via PF_KEY and migrating it.
Mitigation Recommendations
A fix is available that initializes the alg_key_len field to zero in the IPComp compression algorithm structure, preventing uninitialized memory usage. Users should update their Linux kernel to a version that includes this fix. Since this is a kernel vulnerability, applying the official kernel patch or upgrading to a fixed kernel release is the recommended remediation. Patch status is not explicitly stated in the input data; check the vendor advisory for the exact fixed kernel versions and apply updates accordingly.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-rcfx-m5g2-2jgr
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-64436"]
- Ecosystems
- []
- Database Specific Severity
- null
- Cvss Version
- null
Threat ID: 6a6542099c2644c7f80835a0
Added to database: 07/25/2026, 23:08:57 UTC
Last enriched: 07/25/2026, 23:22:46 UTC
Last updated: 09/08/2026, 22:52:14 UTC
Views: 53
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.