CVE-2026-74640 — ALSA: FCP: fix OOB write in fcp_meter_ctl_get()
In the Linux kernel, the following vulnerability has been resolved: ALSA: FCP: fix OOB write in fcp_meter_ctl_get() fcp_ioctl_set_meter_map() bounds the user-supplied Level Meter map size by the driver's own limit of 255 if (map.map_size < 1 || map.map_size > 255 || map.meter_slots < 1 || map.meter_slots > 255) return -EINVAL; and passes it to fcp_add_new_ctl() as the control's channel count, where it is stored as elem->channels. Every control read writes into struct snd_ctl_elem_value, whose integer array is declared long value[128], so the limit is 128, not 255. fcp_meter_ctl_get() stores one 64-bit word per channel into that array with no bound of its own: for (i = 0; i < elem->channels; i++) { int idx = private->meter_level_map[i]; int value = idx < 0 ? 0 : le32_to_cpu(resp[idx]); ucontrol->value.integer.value[i] = value; } snd_ctl_elem_read_user() serves that object from memdup_user(_control, sizeof(*control)), 1224 bytes on LP64 out of kmalloc-2048. offsetof(struct snd_ctl_elem_value, value) is 72, so element i is written at byte 72 + 8 * i and element 144 already lands past the allocation. At map_size 255 the last store ends at byte 2112, 888 bytes past the object and 64 bytes into the adjacent slab object. The stored words come from the device and meter_level_map[] selects which word lands in which slot, so extent and contents are both controlled. The core does not catch this. snd_ctl_check_elem_info() is reached only from __snd_ctl_elem_info(), which snd_ctl_elem_read() calls under CONFIG_SND_CTL_DEBUG; without that option snd_ctl_skip_validation() is a compile-time true. __snd_ctl_add_replace() validates kcontrol->count and never inspects elem->channels. Installing an oversized map needs CAP_SYS_RAWIO, but the control outlives the hwdep descriptor that created it, so the out-of-bounds stores are issued by any process able to read controls on /dev/snd/controlC0. KASAN on 7.2.0-rc5 (arm64), triggered by an unprivileged control read: BUG: KASAN: slab-out-of-bounds in fcp_meter_ctl_get Write of size 8 at addr ffff000017af04c8 by task fcp_trigger/185 __asan_store8 fcp_meter_ctl_get snd_ctl_elem_read snd_ctl_ioctl Allocated by task 185: memdup_user snd_ctl_ioctl The buggy address is located 0 bytes to the right of allocated 1224-byte region [ffff000017af0000, ffff000017af04c8) Bound the map size by the ABI limit rather than by 255, and bound the store loop at the sink so it cannot run past the value array whatever elem->channels holds. Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.2% (30-day exploitation probability)+1
- Technical severity (high)+6
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Linux Linux).
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Search available logs for exploit probes, errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Linux | Linux | ≥ 46757a3e7d50dac923888e7fbe68377736f13c70 and < bb30e35c36ed00f24fa39aded811f64230a913b0≥ 46757a3e7d50dac923888e7fbe68377736f13c70 and < bb61dc2ae59026f76db26e1909746908bc5b6f31≥ 46757a3e7d50dac923888e7fbe68377736f13c70 and < 620f1e52a46f604635efd0fb78138afd6a513b5dversion 6.14 | Vulnerable | CVE Program (cve.org) e CISA ADP |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 7.8 | CVSS 3.1 | High | 1.8 | 5.9 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 via NIST National Vulnerability Database |
| 7.8 | CVSS 3.1 | High | — | — | GitHub, Inc. via GitHub Security Advisories |
| 7.8 | CVSS 3.1 | High | — | — | Linux via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (score shown at the top: 416baaa9-dc9f-4396-8d5f-8c081fb06d67) EPSS over time FIRST
Oct 13, 2026 → Oct 15, 2026 · 3 reading(s) · max 0.17%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · linux/linux
- Record published
- CVSS changed · 7.8
- Source status changed · → Received
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× References added · Oct 14, 2026 – Oct 14, 2026
- 1× Official description updated · Oct 14, 2026 – Oct 14, 2026
References
5 on the record
Elsewhere on this site
Related CVEs (same products)
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- Unknown CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 1d
- Unknown CVE-2026-98424 wifi: cfg80211: undo netns switch if renaming the wiphy fails 2d
- Unknown CVE-2026-98425 wifi: mac80211: don't warn when an IBSS has no channel to scan 2d
- Unknown CVE-2026-98426 wifi: mwifiex: fix IRQ leak using wrong index in MSI-X error path 2d
- Unknown CVE-2026-98427 net/sched: codel: bound the dropping loop per dequeue call 2d
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No fixed version, patch or mitigation documented.
- No CISA SSVC assessment.
- No CWE classification.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-74640 is "ALSA: FCP: fix OOB write in fcp_meter_ctl_get()", rated High. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.8 describes technical severity. EPSS 0.17% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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