CVE-2026-70629
Description
A flaw was found in FFmpeg. An uninitialized heap memory read vulnerability exists in the native RSCC decoder. An attacker can supply a crafted video file with a compressed tile that decompresses fewer bytes than required. This leads to the unwritten portion of an intermediate buffer being copied into the decoded frame, potentially exposing data from prior heap allocations or previous decoded frames.
Statement
An uninitialized heap memory disclosure flaw exists in FFmpeg's native RSCC decoder within libavcodec/rscc.c. When decoding a crafted video file containing a truncated compressed tile, rscc_decode_frame() fails to validate the decompressed byte count before invoking av_image_copy_plane(). Consequently, unwritten heap memory in the persistent ctx->inflated_buf buffer is copied directly into rendered frame output. When FFmpeg runs in persistent or shared-process services, processing untrusted media can expose sensitive heap memory contents, posing a High impact to confidentiality.
Mitigation
Avoid processing untrusted RSCC-encoded video files using FFmpeg in persistent or multi-tenant services. If decoding untrusted media is required, execute FFmpeg inside an ephemeral container or isolated systemd sandbox to prevent sensitive cross-session heap data exposure.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.5 | N/A | 5.5 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | Required | N/A | Required |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | None | N/A | None |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
cve.org: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory; Read Application Data
When reusing a resource such as memory or a program variable, the original contents of that resource may not be cleared before it is sent to an untrusted party.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
The uninitialized resource may contain values that cause program flow to change in ways that the programmer did not intend.
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