CVE-2026-125187 (CVSS 5.5)

Description

FFmpeg through 9.0.2 contains a reachable assertion vulnerability in the TTA encoder's tta_encode_frame() in libavcodec/ttaenc.c, which never reserves output packet space for the 4-byte CRC. Attackers can supply audio whose sample values and length produce a small, poorly compressible final frame, triggering the av_assert0() in flush_put_bits() and aborting applications transcoding to TTA.

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CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

EPSS — Exploit Prediction

0.0017

Probability of exploitation

0.06%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-617 CWE-617

References

Other References

https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25694 https://github.com/FFmpeg/FFmpeg https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/ttaenc.c#L93 https://github.com/FFmpeg/FFmpeg/commit/29a629e788c4343ff2e923095b8f38769fe2e470 https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-tta-encoder-reachable-assertion-via-tta-encode-frame

Frequently Asked Questions

What is CVE-2026-125187? +

FFmpeg through 9.0.2 contains a reachable assertion vulnerability in the TTA encoder's tta_encode_frame() in libavcodec/ttaenc.c, which never reserves output packet space for the 4-byte CRC. Attackers can supply audio whose sample values and length produce a small, poorly compressible final frame, triggering the av_assert0() in flush_put_bits() and aborting applications transcoding to TTA. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2026-125187? +

CVE-2026-125187 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0017, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-125187? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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