high CVSS 7.8

CVE-2023-52799·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: jfs: fix array-index-out-of-bounds in dbFindLeaf Currently while searching for dmtree_t for sufficient free blocks there is an array out of bounds while getting element in tp->dm_stree. To add the required check for out of bound we first need to determine the type of dmtree. Thus added an extra parameter to dbFindLeaf so that the type of tree can be determined and the required check can be applied.

Severity
high
Software
Kernel
Fixed in
6.6.3
Published
2024-05-21

Affected versions

From: 6.6

Until: 6.6.3

Fixed in: 6.6.3

How to fix this CVE

Update the Linux kernel to version 6.6.3 or later to patch the array-index-out-of-bounds vulnerability in the JFS filesystem's dbFindLeaf function. This flaw could allow local attackers with standard user privileges to crash the system or potentially execute code by triggering improper memory access during disk space allocation operations. Apply the kernel update promptly and reboot your system to activate the patched version.

sudo dnf update kernel kernel-devel && sudo reboot

Defensia detects this vulnerability

How to check if you are affected

  1. Check installed kernel version: uname -r (should be 6.6.3 or later; versions 6.6.0 through 6.6.2 are vulnerable)
  2. Verify JFS filesystem is in use: grep -i jfs /proc/filesystems or mount | grep jfs (if empty, this CVE does not affect your system)
  3. Search system logs for kernel panics or out-of-bounds memory errors: sudo journalctl -u kernel | grep -iE 'out.of.bounds|jfs|dbFindLeaf|array.index'
  4. Confirm the patch is applied by checking kernel build info: cat /proc/version and verify the build date is after the patch release date (June 2024 for stable kernels)

FAQ

What is CVE-2023-52799?

CVE-2023-52799 is a memory safety vulnerability in the Linux kernel's JFS (Journaled File System) module where the dbFindLeaf function fails to validate array indices before accessing the dmtree_t structure, potentially causing a system crash or memory corruption.

Is CVE-2023-52799 being actively exploited?

No, according to CISA's Known Exploited Vulnerabilities catalog, CVE-2023-52799 is not actively exploited in the wild, and no public exploits are available.

What versions of Kernel are affected by CVE-2023-52799?

Linux kernel versions 6.6 through 6.6.2 are affected. Version 6.6.3 and later contain the fix. Kernels outside the 6.6.x branch are unaffected.

How do I check if my server is vulnerable to CVE-2023-52799?

Run 'uname -r' and check if the output shows a version between 6.6.0 and 6.6.2. If your kernel is 6.6.3 or higher, or uses a different major.minor version, you are not vulnerable. Additionally verify JFS is actively used with 'mount | grep jfs'.

Does Defensia detect CVE-2023-52799?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If the Linux kernel is installed on a monitored server with versions 6.6.0 through 6.6.2, CVE-2023-52799 will appear in your dashboard with remediation steps and priority alerts.

Related Kernel CVEs

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CVE-2026-64355CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: bpf: Reject fragmented frames in devmap Devmap broadcast redirects clone the packet for all but the last destination. For native XDP, that clone path copies only the linear xdp_frame data, while fragmented frames keep skb_shared_info in tailroom outside the linear area. Cloning such a frame leaves XDP_FLAGS_HAS_FRAGS set but without valid frag metadata, and the later free path can interpret uninitialized tail data as skb_shared_info, leading to an out-of-bounds access during frame return. Reject fragmented native XDP frames in dev_map_enqueue_clone(). Add the same restriction to the generic XDP clone path in dev_map_redirect_clone(). Generic XDP represents fragmented packets as nonlinear skbs, and rejecting them here keeps clone-based broadcast support aligned between native and generic XDP.
CVE-2026-63993CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu() skb_tunnel_check_pmtu() can change skb->head. Reusing old_iph afer skb_tunnel_check_pmtu() can cause an UAF. Use instead ip_hdr(skb) as done in drivers/net/bareudp.c and drivers/net/geneve.c. Found by Sashiko.
CVE-2026-43501CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: ipv6: rpl: reserve mac_len headroom when recompressed SRH grows ipv6_rpl_srh_rcv() decompresses an RFC 6554 Source Routing Header, swaps the next segment into ipv6_hdr->daddr, recompresses, then pulls the old header and pushes the new one plus the IPv6 header back. The recompressed header can be larger than the received one when the swap reduces the common-prefix length the segments share with daddr (CmprI=0, CmprE>0, seg[0][0] != daddr[0] gives the maximum +8 bytes). pskb_expand_head() was gated on segments_left == 0, so on earlier segments the push consumed unchecked headroom. Once skb_push() leaves fewer than skb->mac_len bytes in front of data, skb_mac_header_rebuild()'s call to: skb_set_mac_header(skb, -skb->mac_len); will store (data - head) - mac_len into the u16 mac_header field, which wraps to ~65530, and the following memmove() writes mac_len bytes ~64KiB past skb->head. A single AF_INET6/SOCK_RAW/IPV6_HDRINCL packet over lo with a two segment type-3 SRH (CmprI=0, CmprE=15) reaches headroom 8 after one pass; KASAN reports a 14-byte OOB write in ipv6_rthdr_rcv. Fix this by expanding the head whenever the remaining room is less than the push size plus mac_len, and request that much extra so the rebuilt MAC header fits afterwards.
CVE-2026-64216CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: netfs: Fix potential UAF in netfs_unlock_abandoned_read_pages() netfs_unlock_abandoned_read_pages(rreq) accesses the index of the folios it is wanting to unlock and compares that to rreq->no_unlock_folio so that it doesn't unlock a folio being read for netfs_perform_write() or netfs_write_begin(). However, given that netfs_unlock_abandoned_read_pages() is called _after_ NETFS_RREQ_IN_PROGRESS is cleared, the one folio that it's not allowed to dereference is the one specified by ->no_unlock_folio as ownership immediately reverts to the caller. Fix this by storing the folio pointer instead and using that rather than the index. Also fix netfs_unlock_read_folio() where the same applies.

References

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