CVE-2026-75143

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-08-19. a secondary CVSS source baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.8Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

FFmpeg before commit 1c10bcc contains a heap buffer overflow in the RIST protocol reader (libavformat/librist.c). librist_read() ignored its size argument and copied the full received payload length into the caller-provided destination buffer, overflowing it when the payload exceeds the destination size. This is reachable via the async:rist:// URL scheme, where the async wrapper supplies a smaller buffer than the received payload. A remote RIST sender can trigger the overflow by sending a packet whose payload exceeds the caller buffer size.

CVSS v3
9.8
EG Score
9.8(high)
EG Risk
59(Track)
EG Risk 59/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
34%
KEV
Not listed

Published

August 19, 2026

Last Modified

August 21, 2026

Advisory Details (3)

Auto-updated Aug 21, 2026
No patch confirmed yet.
generic

FFmpeg Heap Buffer Overflow via RIST Protocol Reader | Advisories | VulnCheck

https://www.vulncheck.com/advisories/ffmpeg-heap-buffer-overflow-via-rist-protocol-reader
generic

#24089 - avformat/librist: honor the caller buffer size in librist_read - FFmpeg/FFmpeg - FFmpeg Forgejo

https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24089
generic

avformat/librist: honor the caller buffer size in librist_read · 1c10bcc2e1 - FFmpeg/FFmpeg - FFmpeg Forgejo

https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/1c10bcc2e17255dacb717a25ab3db142ce390602

Vendor Advisories for CVE-2026-75143(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 20× in last 7d / 20× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-08-21 08:26 UTCGHSA enrichment
  2. 2026-08-21 04:36 UTCEG score recompute
  3. 2026-08-21 04:36 UTCGHSA enrichment
  4. 2026-08-21 04:01 UTCEG score recompute
  5. 2026-08-21 04:01 UTCGHSA enrichment
  6. 2026-08-21 01:29 UTCEG score recompute
  7. 2026-08-21 01:29 UTCGHSA enrichment
  8. 2026-08-20 22:56 UTCEPSS rescore
  9. 2026-08-20 21:40 UTCGHSA enrichment
  10. 2026-08-20 17:50 UTCGHSA enrichment
  11. 2026-08-20 14:00 UTCGHSA enrichment
  12. 2026-08-20 09:49 UTCGHSA enrichment
  13. 2026-08-20 05:59 UTCGHSA enrichment
  14. 2026-08-20 02:08 UTCGHSA enrichment
  15. 2026-08-19 22:19 UTCEG score recompute
  16. 2026-08-19 22:19 UTCGHSA enrichment
  17. 2026-08-19 18:29 UTCEG score recompute
  18. 2026-08-19 17:28 UTCEG score recompute
  19. 2026-08-19 16:43 UTCEG score recompute
  20. 2026-08-19 16:43 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-75143?
CVE-2026-75143 is a critical vulnerability published on August 19, 2026. FFmpeg before commit 1c10bcc contains a heap buffer overflow in the RIST protocol reader (libavformat/librist.c). librist_read() ignored its size argument and copied the full received payload length into the caller-provided destination buffer, overflowing it when the payload exceeds the destination…
When was CVE-2026-75143 disclosed?
CVE-2026-75143 was first published in the National Vulnerability Database on August 19, 2026, with the most recent update on August 21, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-75143 actively exploited?
CVE-2026-75143 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 66.0% of all scored CVEs.
What is the CVSS score of CVE-2026-75143?
CVE-2026-75143 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-75143?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-75143, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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