CVE-2025-59734
It is possible to cause an use-after-free write in SANM decoding with a carefully crafted animation using subversion <2.
When a STOR chunk is present, a subsequent FOBJ chunk will be saved in ctx->stored_frame. Stored frames can later be referenced by FTCH chunks. For files using subversion < 2, the undecoded frame is stored, and decoded again when the FTCH chunks are parsed. However, in process_frame_obj if the frame has an invalid size, there’s an early return, with a value of 0.
This causes the code in decode_frame to still store the raw frame buffer into ctx->stored_frame. Leaving ctx->has_dimensions set to false.
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A subsequent chunk with type FTCH would call process_ftch and decode that frame obj again, adding to the top/left values and calling process_frame_obj again. Given that we never set ctx->have_dimensions before, this time we set the dimensions, calling init_buffers, which can reallocate the buffer in ctx->stored_frame, freeing the previous one. However, the GetByteContext object gb still holds a reference to the old buffer.
Finally, when the code tries to decode the frame, codecs that accept a GetByteContext as a parameter will trigger a use-after-free read when using gb.
GetByteContext is only used for reading bytes, so at most one could read invalid data. There are no heap allocations between the free and when the object is accessed. However, upon returning to process_ftch, the code restores the original values for top/left in stored_frame, writing 4 bytes to the freed data at offset 6, potentially corrupting the allocator’s metadata.
This issue can be triggered just by probing whether a file has the sanm format.
We recommend upgrading to version 8.0 or beyond.
CVSS
- Versión: 4.0
- Vector: CVSS:4.0/AV:A/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- Puntuación base: 8.7
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.18%
- Percentil entre todas las CVEs puntuadas: 7
- 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
T1203Exploitation for Client Executionexecution85 % - Impacto principal
T1059Command and Scripting Interpreterexecution75 % - Impacto secundario
T1499.004Application or System Exploitationimpact60 %
AV:A con UI:P indica explotación en cliente (abrir archivo preparado). Use-after-free permite ejecución de código y DoS por corrupción de memoria de ffmpeg.
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.
CWE
- CWE-416
Referencias
JSON original (NVD)
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{
"id": "CVE-2025-59734",
"cveTags": [],
"metrics": {
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"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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"id": "CVE-2025-59734",
"role": "CISA Coordinator",
"options": [
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{
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"version": "2.0.3",
"timestamp": "2025-10-08T03:55:15.823380Z"
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"valueDensity": "NOT_DEFINED",
"vectorString": "CVSS:4.0/AV:A/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"exploitMaturity": "NOT_DEFINED",
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"vulnerabilityResponseEffort": "NOT_DEFINED",
"modifiedSubAvailabilityImpact": "NOT_DEFINED",
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"affected": [
{
"source": "cve-coordination@google.com",
"affectedData": [
{
"repo": "https://git.ffmpeg.org/ffmpeg.git",
"vendor": "FFmpeg",
"product": "FFmpeg",
"versions": [
{
"status": "affected",
"version": "4d7c609be37dc57d31527c8c9e5945dc9491a7cd",
"lessThan": "8.0",
"versionType": "custom"
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{
"status": "affected",
"version": "7.1.1",
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"versionType": "semver"
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],
"packageName": "SANM",
"collectionURL": "https://git.ffmpeg.org/ffmpeg.git",
"defaultStatus": "unaffected"
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]
}
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"published": "2025-10-06T08:15:35.227",
"references": [
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"url": "https://issuetracker.google.com/440183164",
"source": "cve-coordination@google.com"
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"description": [
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"lang": "en",
"value": "It is possible to cause an use-after-free write in SANM decoding with a carefully crafted animation using subversion <2.\n\nWhen a STOR chunk is present, a subsequent FOBJ chunk will be saved in ctx->stored_frame. Stored frames can later be referenced by FTCH chunks. For files using subversion < 2, the undecoded frame is stored, and decoded again when the FTCH chunks are parsed. However, in process_frame_obj if the frame has an invalid size, there’s an early return, with a value of 0. \n\nThis causes the code in decode_frame to still store the raw frame buffer into ctx->stored_frame. Leaving ctx->has_dimensions set to false.\n\nA subsequent chunk with type FTCH would call process_ftch and decode that frame obj again, adding to the top/left values and calling process_frame_obj again.\nGiven that we never set ctx->have_dimensions before, this time we set the dimensions, calling init_buffers, which can reallocate the buffer in ctx->stored_frame, freeing the previous one. However, the GetByteContext object gb still holds a reference to the old buffer.\n\n\n\n\nFinally, when the code tries to decode the frame, codecs that accept a GetByteContext as a parameter will trigger a use-after-free read when using gb.\n\nGetByteContext is only used for reading bytes, so at most one could read invalid data. There are no heap allocations between the free and when the object is accessed. However, upon returning to process_ftch, the code restores the original values for top/left in stored_frame, writing 4 bytes to the freed data at offset 6, potentially corrupting the allocator’s metadata.\n\nThis issue can be triggered just by probing whether a file has the sanm format.\n\n\n\n\n\n\n\nWe recommend upgrading to version 8.0 or beyond."
}
],
"lastModified": "2026-06-17T09:46:36.900",
"sourceIdentifier": "cve-coordination@google.com"
}