GNU Emacs up to 30.2 TrueType Font Processing src/sfnt.c sfnt_read_cmap_format_12 integer overflow

Summaryinfo

A vulnerability was found in GNU Emacs up to 30.2. It has been declared as critical. Affected is the function sfnt_read_cmap_format_12 of the file src/sfnt.c of the component TrueType Font Processing. Such manipulation leads to integer overflow. This vulnerability is documented as CVE-2026-71392. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in GNU Emacs up to 30.2. It has been rated as critical. Affected by this issue is the function sfnt_read_cmap_format_12 of the file src/sfnt.c of the component TrueType Font Processing. The manipulation with an unknown input leads to a integer overflow vulnerability. Using CWE to declare the problem leads to CWE-190. The product performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. Impacted is confidentiality, integrity, and availability. CVE summarizes:

GNU Emacs for Android is vulnerable to an integer overflow in the sfnt_read_cmap_format_12() function in src/sfnt.c. When processing a crafted TrueType font file, an unguarded addition in the xmalloc allocation call wraps around on 32-bit builds, causing a heap buffer overflow write. An attacker can deliver a malicious font file via email, EWW (Emacs Web Wowser), or documents with custom faces, causing Emacs to load it. This results in heap memory corruption that can lead to code execution. This issue was fixed in commit c4e20777c26548722a37b03db93243e83a0d6188

The advisory is available at cert.pl. This vulnerability is handled as CVE-2026-71392 since 08/06/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit.

Applying the patch c4e20777c26548722a37b03db93243e83a0d6188 is able to eliminate this problem.

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Type

• Word Processing Software

Vendor

• GNU

Name

• Emacs

Version

• 30.0
• 30.1
• 30.2

License

• open-source

Website

• Vendor: https://www.gnu.org/

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CPE 2.2info

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If you want to get best quality of vulnerability data, you may have to visit VulDB.

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