Sources: National Vulnerability Database, CVE.org, CISA KEV, FIRST EPSS
CVE-2026-125210 Overview
FFmpeg through 9.0.2 contains a heap buffer overflow vulnerability in aribcaption_trans_text_subtitle() in libavcodec/libaribcaption.c when decoding with sub_type text. Attackers can supply a crafted ARIB STD-B24 caption stream with zero regions, causing a pointer write past a zero-sized sub->rects allocation and corrupting heap memory.
Critical Impact
Affected Products
- FFmpeg: see the vendor advisory for the exact affected versions
Discovery Timeline
- 2026-11-09: CVE-2026-125210 published to the National Vulnerability Database by disclosure@vulncheck.com
- 2026-11-09: last updated in the NVD database
Technical Details for CVE-2026-125210
Vulnerability Analysis
CVE-2026-125210 is a Security Vulnerability weakness (CWE-131) in FFmpeg. Based on its CVSS vector, the flaw needs local or adjacent access, needs no login, and relies on a user taking an action.
With a CVSS base score of 7.3, apply the vendor fix and confirm exposure on internet facing and business critical assets first.
Root Cause
The vendor description states: FFmpeg through 9.0.2 contains a heap buffer overflow vulnerability in aribcaption_trans_text_subtitle() in libavcodec/libaribcaption.c when decoding with sub_type text. Attackers can supply a crafted ARIB STD-B24 caption stream with zero regions, causing a pointer write past a zero-sized sub->rects allocation and corrupting heap memory.
Attack Vector
Based on the CVSS vector, the flaw needs local or adjacent access, needs no login, and relies on a user taking an action. Attack complexity is high complexity.
No exploitation in the wild is confirmed by CISA at the time of the last update. Check the references below for any vendor or researcher proof of concept.
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
Detection Methods for CVE-2026-125210
Detection Strategies
- Inventory every instance of FFmpeg and compare the running version with the affected range above.
- Check external attack surface scans for internet facing instances of the component.
- Run an authenticated vulnerability scan once your scanner ships a check for this CVE.
Monitoring Recommendations
- Forward FFmpeg application, access and audit logs to your SIEM for retrospective hunting.
- Alert on new processes, configuration changes or outbound connections from the affected service.
- Track the vendor advisory and the CISA KEV catalog for changes in exploitation status.
How to Mitigate CVE-2026-125210
Immediate Actions Required
- Apply the fixed version of FFmpeg named in the vendor advisory.
- Prioritize internet facing and business critical instances first.
- Rescan after the change to confirm the exposure is closed.
Patch Information
Use the fixed version listed in the vendor advisory for FFmpeg.
Workarounds
- If patching must wait, restrict network access to the affected service and place it behind authentication or a web application firewall rule.
CWE References
Technical References
This entry is built directly from NVD, CISA KEV and EPSS data. Verify fixed versions in the vendor advisory before you deploy.
Frequently asked questions
Related CVEs
FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.24.0, the gdi_surface_bits() function processes SURFACE_BITS_COMMAND messages sent by the RDP server. When the command is handled using NSCodec, the bmp.width and bmp.height values provided by the server are not properly validated against the actual desktop dimensions. A malicious RDP server can supply crafted bmp.width and bmp.height values that exceed the expected surface size. Because these values are used during bitmap decoding and memory operations without proper bounds checking, this can lead to a heap buffer overflow. Since the attacker can also control the associated pixel data transmitted by the server, the overflow may be exploitable to overwrite adjacent heap memory. This vulnerability is fixed in 3.24.0.
NLnet Labs Unbound 1.14.0 up to and including version 1.25.0 has a vulnerability that results in heap overflow when encoding multiple NSID and/or DNS Cookie EDNS and/or EDNS Padding options in the reply packet. The relevant options ('nsid', 'answer-cookie', 'pad-responses' (default)) need to be enabled for the vulnerability to be exploited. An adversary who can query Unbound can exploit the vulnerability by attaching multiple NSID and/or DNS Cookie EDNS and/or EDNS Padding options to the query. A flaw in the size calculation of the EDNS field truncates the correct value which allows the encoder to overflow the available space when writing. Those two combined lead to a heap overflow write of Unbound controlled data and eventually a crash. Unbound 1.25.1 contains a patch with a fix to de-duplicate the EDNS options and a fix to prevent truncation of the EDNS field size calculation.
An Incorrect Calculation of Buffer Size vulnerability in the routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows a configured eBGP neighbor to cause an rpd crash via BGP labeled-unicast UPDATEs when the affected multipath features are enabled.
FFmpeg through 9.0.2 contains a heap buffer overflow vulnerability in dvbsub_encode() in libavcodec/dvbsubenc.c that undercounts each CLUT segment header by two bytes. Attackers can supply a file with many bitmap subtitle rectangles that, when transcoded to the dvbsub encoder, writes past the output buffer and corrupts heap memory.
FFmpeg before 8.1.3 and 9.x before 9.0.2 contains a heap buffer overflow vulnerability in the DVD subtitle encoder that underestimates RLE output size for odd-width rectangles. Attackers can supply files with crafted bitmap subtitles that, when transcoded to the dvdsub encoder, write past the output buffer and corrupt heap memory.
rsync 3.2.3 before 3.5.0 contains an out-of-bounds write in parse_size_arg() where the return value of snprintf() is used directly as an index into a .bss-segment array without bounds checking. When snprintf truncates the formatted size string, the return value equals the number of characters that would have been written including the truncated portion, and this value may exceed the array length. The subsequent indexed write targets memory outside the intended array bounds, corrupting .bss memory.
Earn your free CTEM certification.
Learn to scope, prioritize, validate and mobilize fixes for CVEs like CVE-2026-125210 with a free CTEM certification.
Beginner / Practitioner / Program Leader
Explore certifications