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Vulnerability record

CVE-2026-125257

highCVSS 4.0 7.3EPSS 0.14%Published · FFmpeg

The short answer

CVE-2026-125257 affects FFmpeg FFmpeg and is rated high (CVSS 7.3). It is not in CISA's KEV catalog; EPSS puts the chance of exploitation in the next 30 days at 0.14%.

What it is

FFmpeg through 9.0.2 contains an off-by-one heap overflow vulnerability in get_exponent_dynamic() in libavcodec/nellymoserenc.c that allows writing one element past the opt and path allocations. Attackers can supply crafted audio to applications encoding Nellymoser with trellis enabled, causing idx to equal OPT_SIZE and overwrite adjacent heap memory.

Weakness: CWE-193.

Severity

7.3 high

CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/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

Exploited (CISA KEV)

Not listed

CISA lists confirmed exploitation only

EPSS, next 30 days

0.14%

Higher than 4% of scored CVEs

How it can be exploited

Attack vector
Local
Attack complexity
High
Attack requirements
Present
Privileges required
None
User interaction
Passive
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Affected products

FFmpeg. NVD's record lists the exact affected versions.

References

Questions

Is CVE-2026-125257 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog as of 2026-11-11. FIRST's EPSS estimates a 0.14% chance of exploitation in the next 30 days.

How do I fix CVE-2026-125257?

Follow the vendor advisory in the references below. NVD lists the affected versions under its configurations.

From NVD, CISA KEV, FIRST EPSS and OSV.dev, checked . Status on NVD: Awaiting Analysis. The description is NVD's text, quoted as published.

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