Platform
c
Component
libexif
Fixed in
0.6.26
CVE-2026-40386 describes an integer underflow vulnerability discovered in libexif, a library for reading and writing EXIF data in image files. This flaw allows attackers to potentially crash applications using libexif or leak sensitive information. The vulnerability affects versions from 0.0.0 through 0.6.25 and has been resolved in version 0.6.26.
The integer underflow occurs during the decoding of Fuji and Olympus MakerNotes within EXIF data. An attacker could craft a malicious image file containing specifically crafted MakerNote data that triggers the underflow. This could lead to a denial-of-service (DoS) condition by crashing the application processing the image. More concerningly, the underflow could potentially be exploited to leak information from the application's memory, depending on how libexif is integrated and used within the larger system. The potential for information leakage makes this vulnerability a significant concern, particularly in applications handling untrusted image data.
CVE-2026-40386 was publicly disclosed on 2026-04-12. As of this writing, there are no publicly available proof-of-concept exploits. The vulnerability is not currently listed on the CISA KEV catalog. The CVSS score of 4.0 indicates a medium severity, suggesting a moderate probability of exploitation if a suitable exploit is developed.
Exploit Status
EPSS
0.01% (2% percentile)
CISA SSVC
CVSS Vector
The primary mitigation for CVE-2026-40386 is to upgrade to libexif version 0.6.26 or later. If upgrading is not immediately feasible due to compatibility issues or system downtime constraints, consider implementing input validation on EXIF data, specifically focusing on Fuji and Olympus MakerNotes. This could involve limiting the size of these notes or performing stricter checks on their contents. While not a complete solution, this can reduce the attack surface. Additionally, monitor application logs for crashes or unexpected behavior related to image processing, which could indicate exploitation attempts. After upgrading, confirm the fix by processing a known malicious image file (if available) and verifying that the application does not crash or exhibit unusual behavior.
Update to version 0.6.26 or later of libexif to mitigate the vulnerability. This update fixes an integer overflow error in Fuji and Olympus MakerNote decoding, preventing potential crashes or information leaks.
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CVE-2026-40386 is a medium severity vulnerability in libexif versions 0.0.0–0.6.25 where an integer underflow in MakerNote decoding can cause crashes or information leaks.
You are affected if your system uses libexif versions 0.0.0 through 0.6.25 and processes image files, especially those from untrusted sources.
Upgrade to libexif version 0.6.26 or later. As a temporary workaround, implement input validation on Fuji and Olympus MakerNotes.
As of the current date, there are no confirmed reports of active exploitation, but a public proof-of-concept could emerge at any time.
Refer to the libexif project's official website or security mailing list for the latest advisory and updates regarding CVE-2026-40386.
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