high CVSS 7.8

CVE-2023-52603·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: UBSAN: array-index-out-of-bounds in dtSplitRoot Syzkaller reported the following issue: oop0: detected capacity change from 0 to 32768 UBSAN: array-index-out-of-bounds in fs/jfs/jfs_dtree.c:1971:9 index -2 is out of range for type 'struct dtslot [128]' CPU: 0 PID: 3613 Comm: syz-executor270 Not tainted 6.0.0-syzkaller-09423-g493ffd6605b2 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1b1/0x28e lib/dump_stack.c:106 ubsan_epilogue lib/ubsan.c:151 [inline] __ubsan_handle_out_of_bounds+0xdb/0x130 lib/ubsan.c:283 dtSplitRoot+0x8d8/0x1900 fs/jfs/jfs_dtree.c:1971 dtSplitUp fs/jfs/jfs_dtree.c:985 [inline] dtInsert+0x1189/0x6b80 fs/jfs/jfs_dtree.c:863 jfs_mkdir+0x757/0xb00 fs/jfs/namei.c:270 vfs_mkdir+0x3b3/0x590 fs/namei.c:4013 do_mkdirat+0x279/0x550 fs/namei.c:4038 __do_sys_mkdirat fs/namei.c:4053 [inline] __se_sys_mkdirat fs/namei.c:4051 [inline] __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4051 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7fcdc0113fd9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffeb8bc67d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000102 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fcdc0113fd9 RDX: 0000000000000000 RSI: 0000000020000340 RDI: 0000000000000003 RBP: 00007fcdc00d37a0 R08: 0000000000000000 R09: 00007fcdc00d37a0 R10: 00005555559a72c0 R11: 0000000000000246 R12: 00000000f8008000 R13: 0000000000000000 R14: 00083878000000f8 R15: 0000000000000000 </TASK> The issue is caused when the value of fsi becomes less than -1. The check to break the loop when fsi value becomes -1 is present but syzbot was able to produce value less than -1 which cause the error. This patch simply add the change for the values less than 0. The patch is tested via syzbot.

Severity
high
Software
Kernel
Fixed in
6.7.4
Published
2024-03-06

Affected versions

From: 6.7

Until: 6.7.4

Fixed in: 6.7.4

How to fix this CVE

Update your Linux kernel to version 6.7.4 or later to resolve this array bounds vulnerability in the JFS filesystem driver. The vulnerability allows a negative array index to be accessed during directory tree splitting operations, which can be triggered through crafted filesystem operations. Systems using JFS should prioritize this update to prevent potential kernel panics and memory corruption.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Check installed kernel version: uname -r — verify the version is 6.7.4 or later
  2. Verify JFS filesystem usage: mount | grep jfs — identify if JFS is mounted on the system
  3. Review kernel logs for array bounds errors: dmesg | grep -i 'out.of.bounds\|ubsan\|dtSplitRoot' — look for UBSAN violations in the jfs_dtree module
  4. Confirm the fix: grep 'fsi.*<.*0' /boot/config-$(uname -r) — verify the patched bounds check is present in the running kernel

FAQ

What is CVE-2023-52603?

CVE-2023-52603 is an array index out-of-bounds vulnerability in the Linux kernel's JFS (Journaled File System) implementation. It occurs in the dtSplitRoot function when a negative array index is used to access the dtslot array, potentially leading to kernel crashes or memory corruption during directory tree splitting operations.

Is CVE-2023-52603 being actively exploited?

No, CVE-2023-52603 is not listed in the CISA Known Exploited Vulnerabilities catalog and no public exploits are currently available. However, the vulnerability was discovered through fuzzing (Syzkaller), indicating it can be reliably triggered with crafted filesystem operations.

What versions of Kernel are affected by CVE-2023-52603?

Linux kernel versions 6.7 through 6.7.3 are vulnerable. The vulnerability is fixed in kernel version 6.7.4 and later. Older stable branches may also be affected depending on backports.

How do I check if my server is vulnerable to CVE-2023-52603?

Run 'uname -r' to check your kernel version and verify it is 6.7.4 or later. Additionally, check if JFS is in use with 'mount | grep jfs' — systems without JFS mounted are not vulnerable to this specific issue.

Does Defensia detect CVE-2023-52603?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If the Linux kernel is installed on a monitored server, CVE-2023-52603 will appear in your dashboard with remediation steps.

Related Kernel CVEs

CVE-2026-63994CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]() Sashiko found that iptunnel_pmtud_build_icmp() and iptunnel_pmtud_build_icmpv6() were caching ip_hdr() and ipv6_hdr() before an skb_cow() call which can reallocate skb->head. Fix this possible UAF by initializing the local variables after the skb_cow() call. Remove skb_reset_network_header() calls which were not needed.
CVE-2026-64025CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: bpf, skmsg: fix verdict sk_data_ready racing with ktls rx sk_psock_strp_data_ready() already checks tls_sw_has_ctx_rx() and defers to psock->saved_data_ready when a TLS RX context is present, avoiding a conflict with the TLS strparser's ownership of the receive queue (commit e91de6afa81c, "bpf: Fix running sk_skb program types with ktls"). sk_psock_verdict_data_ready() has no equivalent guard. When a socket is inserted into a sockmap (BPF_SK_SKB_VERDICT) before TLS RX is configured, tls_sw_strparser_arm() saves sk_psock_verdict_data_ready as rx_ctx->saved_data_ready. On data arrival: tls_data_ready -> tls_strp_data_ready -> tls_rx_msg_ready -> saved_data_ready() = sk_psock_verdict_data_ready() -> tcp_read_skb() drains sk_receive_queue via __skb_unlink() without calling tcp_eat_skb(), so copied_seq is not advanced. tls_strp_msg_load() then finds tcp_inq() >= full_len (stale), calls tcp_recv_skb() on the now-empty queue, hits WARN_ON_ONCE(!first), and returns with rx_ctx->strp.anchor.frag_list pointing at a psock-owned (potentially freed) skb. tls_decrypt_sg() subsequently walks that frag_list: use-after-free. Apply the same fix as sk_psock_strp_data_ready(): if a TLS RX context is present, call psock->saved_data_ready (sock_def_readable) to wake recv() waiters and return immediately, leaving the receive queue untouched. TLS retains sole ownership of the queue and decrypts the record normally through tls_sw_recvmsg().
CVE-2026-100075CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: RDMA/srpt: Fix srpt_alloc_rw_ctxs() unwind counters When srpt_alloc_rw_ctxs() fails partway through a multi-buffer indirect descriptor, the unwind path destroys RDMA contexts but leaves stale n_rw_ctx and n_rdma values (and a dangling rw_ctxs pointer). Later sq_wr_avail accounting in srpt_queue_response() or srpt_write_pending() can then subtract the wrong number of send queue credits. Reset the counters and clear rw_ctxs after freeing the heap allocation before returning an error.
CVE-2026-64000CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: net: hsr: fix potential OOB access in supervision frame handling Ensure the entire TLV header is linearized before access by adding sizeof(struct hsr_sup_tlv) to the pskb_may_pull() calls. Without this, a truncated frame could cause an out-of-bounds access.
CVE-2026-64439CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: crypto: krb5 - filter out async aead implementations at alloc krb5_aead_encrypt(), krb5_aead_decrypt() in rfc3961_simplified.c and rfc8009_encrypt(), rfc8009_decrypt() in rfc8009_aes2.c set a NULL completion callback and treat any negative return from crypto_aead_{encrypt,decrypt}() as terminal, falling through to kfree_sensitive(buffer). When the encrypt_name resolves to an async AEAD instance the request returns -EINPROGRESS, the buffer is freed while the backend's worker still holds a pointer, and the worker dereferences the freed slab on completion. KASAN report under UML+SLUB with a synthetic async aead backend bound to krb5->encrypt_name: BUG: KASAN: slab-use-after-free in t5_stub_complete+0x7d/0xc7 The helpers were written synchronously, so filter the async instances out at allocation time instead of plumbing crypto_wait_req() through every call site. Reachable via net/rxrpc/rxgk.c, fs/afs/cm_security.c and net/ceph/crypto.c on systems with an async AEAD provider bound to the krb5 enctype name.

References

Track CVEs across your fleet automatically

Defensia scans your Linux servers and tells you exactly which ones are running vulnerable versions — including CVE-2023-52603. Free for 1 server.

Get started free