CVE-2026-63883
Estado: Pendiente de análisisAlta (7.3)—
In the Linux kernel, the following vulnerability has been resolved:
serial: qcom_geni: fix kfifo underflow when flush precedes DMA completion IRQ
When uart_flush_buffer() runs before the DMA completion IRQ is delivered, the following race can occur (all steps serialized by uart_port_lock):
uart_xmit_advance() increments kfifo->out by tx_remaining. Since kfifo_reset() already set both in and out to 0, out wraps past in, causing kfifo_len() to return UART_XMIT_SIZE - tx_remaining. The next start_tx_dma() call then submits a DMA transfer of stale buffer data.
Fix this by snapshotting kfifo_len() at the start of handle_tx_dma() and skipping uart_xmit_advance() when fifo_len < tx_remaining, which indicates the kfifo was reset by a preceding flush.
Detalles técnicos trazas, registros y código del informe original
1. DMA starts: tx_remaining = N, kfifo contains N bytes
2. DMA completes in hardware; IRQ is pending but not yet delivered
3. uart_flush_buffer() acquires the port lock and calls kfifo_reset(),
making kfifo_len() = 0 while tx_remaining remains N
4. uart_flush_buffer() releases the port lock
5. DMA IRQ fires; handle_tx_dma() acquires the port lock and calls
uart_xmit_advance(uport, tx_remaining) on an empty kfifoCVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L
- Puntuación base: 7.3
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.17%
- Percentil entre todas las CVEs puntuadas: 6
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1068Exploitation for Privilege Escalationprivilege escalation75 % - Impacto principal
T1059Command and Scripting Interpreterexecution60 % - Impacto secundario
T1499.004Application or System Exploitationimpact55 %
Vulnerabilidad local (AV:L, PR:L) en kernel Linux que causa condición de carrera en DMA; permite ejecución de código o DoS por corrupción de buffer. Requiere acceso local con permisos limitados.
Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.
🛡️ Mitigaciones ATT&CK que cubren estas técnicas
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
- https://git.kernel.org/stable/c/0d2c41a8b00934ddf8a7c1b4cf72dffa1e629c46
- https://git.kernel.org/stable/c/452d6fa37ae9b021f4f6d397dbae077f7296f6f4
- https://git.kernel.org/stable/c/654f45a8569f3cd6ff20bd724a18e0cce65893ba
- https://git.kernel.org/stable/c/b1159dce10b38eb795e4c96cdc4d34b83cec81c5
- https://git.kernel.org/stable/c/c91ea13375f70f6271a0183445e34e83b8f4d8f7
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-63883",
"cveTags": [],
"metrics": {
"cvssMetricV31": [
{
"type": "Secondary",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"cvssData": {
"scope": "UNCHANGED",
"version": "3.1",
"baseScore": 7.3,
"attackVector": "LOCAL",
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L",
"integrityImpact": "HIGH",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"availabilityImpact": "LOW",
"privilegesRequired": "LOW",
"confidentialityImpact": "HIGH"
},
"impactScore": 5.5,
"exploitabilityScore": 1.8
}
]
},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "2aaa43c7077833301c237684cd7bc9ae5e3dec95",
"lessThan": "c91ea13375f70f6271a0183445e34e83b8f4d8f7",
"versionType": "git"
},
{
"status": "affected",
"version": "2aaa43c7077833301c237684cd7bc9ae5e3dec95",
"lessThan": "b1159dce10b38eb795e4c96cdc4d34b83cec81c5",
"versionType": "git"
},
{
"status": "affected",
"version": "2aaa43c7077833301c237684cd7bc9ae5e3dec95",
"lessThan": "654f45a8569f3cd6ff20bd724a18e0cce65893ba",
"versionType": "git"
},
{
"status": "affected",
"version": "2aaa43c7077833301c237684cd7bc9ae5e3dec95",
"lessThan": "0d2c41a8b00934ddf8a7c1b4cf72dffa1e629c46",
"versionType": "git"
},
{
"status": "affected",
"version": "2aaa43c7077833301c237684cd7bc9ae5e3dec95",
"lessThan": "452d6fa37ae9b021f4f6d397dbae077f7296f6f4",
"versionType": "git"
}
],
"programFiles": [
"drivers/tty/serial/qcom_geni_serial.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.3"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.3",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.6.143",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.93",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.35",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.0.12",
"versionType": "semver",
"lessThanOrEqual": "7.0.*"
},
{
"status": "unaffected",
"version": "7.1",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"drivers/tty/serial/qcom_geni_serial.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-07-19T16:17:05.343",
"references": [
{
"url": "https://git.kernel.org/stable/c/0d2c41a8b00934ddf8a7c1b4cf72dffa1e629c46",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/452d6fa37ae9b021f4f6d397dbae077f7296f6f4",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/654f45a8569f3cd6ff20bd724a18e0cce65893ba",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/b1159dce10b38eb795e4c96cdc4d34b83cec81c5",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/c91ea13375f70f6271a0183445e34e83b8f4d8f7",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Awaiting Analysis",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nserial: qcom_geni: fix kfifo underflow when flush precedes DMA completion IRQ\n\nWhen uart_flush_buffer() runs before the DMA completion IRQ is delivered,\nthe following race can occur (all steps serialized by uart_port_lock):\n\n 1. DMA starts: tx_remaining = N, kfifo contains N bytes\n 2. DMA completes in hardware; IRQ is pending but not yet delivered\n 3. uart_flush_buffer() acquires the port lock and calls kfifo_reset(),\n making kfifo_len() = 0 while tx_remaining remains N\n 4. uart_flush_buffer() releases the port lock\n 5. DMA IRQ fires; handle_tx_dma() acquires the port lock and calls\n uart_xmit_advance(uport, tx_remaining) on an empty kfifo\n\nuart_xmit_advance() increments kfifo->out by tx_remaining. Since\nkfifo_reset() already set both in and out to 0, out wraps past in,\ncausing kfifo_len() to return UART_XMIT_SIZE - tx_remaining. The next\nstart_tx_dma() call then submits a DMA transfer of stale buffer data.\n\nFix this by snapshotting kfifo_len() at the start of handle_tx_dma()\nand skipping uart_xmit_advance() when fifo_len < tx_remaining, which\nindicates the kfifo was reset by a preceding flush."
}
],
"lastModified": "2026-07-27T17:44:23.777",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}