high CVSS 7

CVE-2024-26654·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: ALSA: sh: aica: reorder cleanup operations to avoid UAF bugs The dreamcastcard->timer could schedule the spu_dma_work and the spu_dma_work could also arm the dreamcastcard->timer. When the snd_pcm_substream is closing, the aica_channel will be deallocated. But it could still be dereferenced in the worker thread. The reason is that del_timer() will return directly regardless of whether the timer handler is running or not and the worker could be rescheduled in the timer handler. As a result, the UAF bug will happen. The racy situation is shown below: (Thread 1) | (Thread 2) snd_aicapcm_pcm_close() | ... | run_spu_dma() //worker | mod_timer() flush_work() | del_timer() | aica_period_elapsed() //timer kfree(dreamcastcard->channel) | schedule_work() | run_spu_dma() //worker ... | dreamcastcard->channel-> //USE In order to mitigate this bug and other possible corner cases, call mod_timer() conditionally in run_spu_dma(), then implement PCM sync_stop op to cancel both the timer and worker. The sync_stop op will be called from PCM core appropriately when needed.

Severity: high
Software: Kernel
Fixed in: 6.8.3
Published: 2024-04-01

Affected versions

From: 6.8

Until: 6.8.3

Fixed in: 6.8.3

How to fix this CVE

Update your Linux kernel to version 6.8.3 or later to resolve a use-after-free vulnerability in the ALSA sound driver for Dreamcast hardware. This flaw could allow local privileged attackers to cause kernel memory corruption through improper synchronization between timer and worker thread cleanup operations. Ensure your system fully reboots after applying the kernel update to activate the patched version.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

Check installed kernel version: uname -r | grep -E '^6\.8\.[0-3]$' — if output appears, you are vulnerable
Verify ALSA Dreamcast driver is loaded: lsmod | grep snd_aica — if empty, the vulnerable component is not present
Monitor kernel logs for memory corruption signs: sudo dmesg | grep -i 'use.after.free\|UAF\|spu_dma\|aica' — exploitation may trigger kernel oops messages
After patching, confirm kernel version: uname -r | grep -E '^6\.8\.[4-9]|6\.[9-9]' — should return patched version

FAQ

What is CVE-2024-26654?

CVE-2024-26654 is a use-after-free vulnerability in the Linux kernel's ALSA Dreamcast sound driver where improper synchronization between a timer and worker thread allows deallocation of audio channel memory while it is still being referenced, leading to kernel memory corruption.

Is CVE-2024-26654 being actively exploited?

No, CVE-2024-26654 is not listed in the CISA Known Exploited Vulnerabilities catalog and no public exploits are currently available. However, it still poses a significant risk for local privilege escalation on affected systems.

What versions of Kernel are affected by CVE-2024-26654?

Kernel versions 6.8 through 6.8.3 are affected. The vulnerability was patched in kernel 6.8.3 and later versions.

How do I check if my server is vulnerable to CVE-2024-26654?

Run 'uname -r' and check if the output matches 6.8.0, 6.8.1, 6.8.2, or 6.8.3. If it does, your system is vulnerable. Then verify the ALSA Dreamcast driver is present with 'lsmod | grep snd_aica'.

Does Defensia detect CVE-2024-26654?

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-2024-26654 will appear in your dashboard with remediation steps.

Related Kernel CVEs

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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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