CVE-2026-70631
Description
A flaw was found in FFmpeg. An attacker can exploit an uninitialized heap memory disclosure vulnerability in the native TIFF decoder by providing a specially crafted TIFF file. This crafted file can cause the tiff_unpack_zlib() function to include stale data from previous memory allocations in the decoded image output. This could potentially expose sensitive information in persistent services.
Statement
An uninitialized heap memory disclosure flaw exists in FFmpeg's native TIFF decoder within libavcodec/tiff.c. When decoding a crafted TIFF file containing an undersized Deflate-compressed strip, tiff_unpack_zlib() fails to verify actual decompressed output length before executing frame-buffer memcpy() operations. This incorporates uninitialized stale heap memory from prior allocations into the rendered image stream. When FFmpeg runs as a persistent service, remote or local users supplying malformed inputs can leak sensitive memory contents, posing a Moderate impact to confidentiality.
Mitigation
Avoid processing untrusted TIFF files using FFmpeg in persistent or shared-process services. If processing untrusted media is required, isolate FFmpeg execution within an ephemeral container or tightly restricted systemd/SELinux sandbox to prevent cross-session memory disclosure.
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
If the uninitialized pointer is used in a read operation, an attacker might be able to read sensitive portions of memory.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If the uninitialized pointer references a memory location that is not accessible to the product, or points to a location that is "malformed" (such as NULL) or larger than expected by a read or write operation, then a crash may occur.
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If the uninitialized pointer is used in a function call, or points to unexpected data in a write operation, then code execution may be possible.
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