CVE-2025-59734

Oct. 6, 2025, 2:56 p.m.

8.7
High

Description

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. 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.

Product(s) Impacted

Vendor Product Versions
*
  • *
  • Sanm
  • <2
  • 8.0

Weaknesses

Common security weaknesses mapped to this vulnerability.

CWE-416
Use After Free
Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.

*CPE(s)

Affected systems and software identified for this CVE.

Type Vendor Product Version Update Edition Language Software Edition Target Software Target Hardware Other Information
a / / <2 / / / / / / /
a / sanm 8.0 / / / / / / /

References

https://b.corp.google.com/issues/440183164

Tags

CWE-416
cve-coordination@google.com
2025-10-06
CVE-2025-59734

CVSS Score

8.7 / 10

CVSS Data - 4.0

  • Attack Vector: ADJACENT
  • Attack Complexity: HIGH
  • Attack Requirements: NONE
  • Privileges Required: NONE
  • User Interaction: PASSIVE
  • Scope:
  • Confidentiality Impact: HIGH
  • Integrity Impact: HIGH
  • Availability Impact: NONE
  • Exploit Maturity: NOT_DEFINED

    • 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

    View Vector String

Timeline

Published: Oct. 6, 2025, 8:15 a.m.
Last Modified: Oct. 6, 2025, 2:56 p.m.

Status : Awaiting Analysis

CVE has been recently published to the CVE List and has been received by the NVD.

More info

Source

cve-coordination@google.com

*Disclaimer: Some vulnerabilities do not have an associated CPE. To enhance the data, we use AI to infer CPEs based on CVE details. This is an automated process and might not always be accurate.