Security Advisory: CVE-2025-71438 - Out-of-Bounds Read in GPAC/MP4Box
Processing a crafted AC-4 stream with an invalid `frame_rate_index` triggers an out-of-bounds read in `gf_odf_ac4_cfg_dsi_v1`, causing MP4Box to crash.
Summary:
The `gf_odf_ac4_cfg_dsi_v1` function in `odf/descriptors.c` uses a stream-supplied `frame_rate_index` to index into fixed-size lookup tables (`AC4_SAMPLE_DELTA_TABLE_48`, `AC4_MEDIA_TIMESCALE_48`). The function does not validate that the index is within bounds before performing the table lookup. A crafted AC-4 file carrying an out-of-range index (e.g., 15) causes an out-of-bounds read, ultimately resulting in a NULL dereference and process crash.
CWE:
CWE-125 - Out-of-bounds Read
Affected Component:
```
odf/descriptors.c:2179
Function: gf_odf_ac4_cfg_dsi_v1()
```
Affected Product:
MP4Box (GPAC Multimedia Open Source Project)
Affected Version:
2.5-DEV-rev1617-g856674b22-master; commit `856674b226d6cbe28a941ad223be38194cbf7d37`. Any codebase equivalent to this commit that has not applied the fix commit is affected.
Attack Conditions:
An attacker supplies a specially crafted AC-4 stream file containing an invalid `frame_rate_index` value. Local access is required; the victim must invoke `MP4Box -dash 100 <crafted_file>` or any equivalent DASH segmentation command that triggers the AC-4 configuration descriptor parsing path.
Impact:
The out-of-bounds read leads to an immediate process crash (SEGV READ at address 0x000000000000), resulting in Denial of Service. No evidence of arbitrary code execution was observed.
Fix / mitigation status:
The issue was fixed in GPAC commit:
```
13eb5b76560aaf7813b865a2ad433258478e2695
```
Users should update to a GPAC build containing this commit or later.
References:
- Issue: https://github.com/gpac/gpac/issues/3303
- PoC: https://github.com/sigdevel/pocs/blob/main/res/gpac/MP4Box/50/50_gf_odf_ac4_cfg_dsi_v1_odf_descriptors_c_2179
- Fix: https://github.com/gpac/gpac/commit/13eb5b76560aaf7813b865a2ad433258478e2695
Credit
Alexander A. Shvedov (@sigdevel)
#fuzzing #infosec #security #afl++ #revers #cybersecurity #bugbounty #vulnerability #opensource #linux #cve #advisory #gpac