CVE-2026-66038

MEDIUMNVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

Score 6.5 from GitHub Security Advisory (severity: HIGH) published 2026-07-24. NVD baseline CVSS 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 4 sources updated this week
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.5Exploit: None knownExposed: 0

A fix is available — apply it.

FFmpeg through 8.1.2, fixed in commit 8670835, contains an information disclosure vulnerability in the LCL/ZLIB video decoder that allows attackers to expose uninitialized heap memory by supplying a valid zlib stream that inflates to fewer bytes than the expected frame size. The zlib_decomp() function in lcldec.c treats short decompression as non-fatal and continues to the RGB24 conversion path, which copies a full frame's worth of rows from the allocation buffer using original frame dimensions, causing uninitialized heap contents including pointer-derived allocator bytes to be copied into the attacker-observable AVFrame output and potentially defeating ASLR in long-lived media processing services.

CVSS v3
6.5
EG Score
6.5(medium)
EG Risk
29(Track)
EG Risk 29/100SSVC: 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
Severity65% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
15%
KEV
Not listed

Published

July 24, 2026

Last Modified

August 7, 2026

Advisory Details (3)

Auto-updated Jul 25, 2026
No patch confirmed yet.
generic

FFmpeg LCL/ZLIB Video Decoder Information Disclosure via lcldec.c | Advisories | VulnCheck

https://www.vulncheck.com/advisories/ffmpeg-lcl-zlib-video-decoder-information-disclosure-via-lcldec-c
generic

#23626 - avcodec/lcldec: zero the not-decoded tail to avoid heap disclosure - FFmpeg/FFmpeg - FFmpeg Forgejo

https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/23626
generic

avcodec/lcldec: zero the not-decoded tail to avoid heap disclosure · e7cbfd1c50 - FFmpeg/FFmpeg - FFmpeg Forgejo

https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/e7cbfd1c507b57a806a5825b87d609963e862c8c

Vendor Advisories for CVE-2026-66038(1)

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

Patch Availability(2)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulibswscale4 (7:3.4.11-0ubuntu0.1+esm13) @ bionic2026-09-15ubuntu
ubuntulibswscale9 (7:8.0.1-3ubuntu2+esm3) @ resolute2026-09-15ubuntu

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
ffmpeg7:4.3.2-0+deb11u2 ... 7:8.1.2-2 (91 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
ffmpeg7:5.1.3-1 ... 7:9.0.1-1 (59 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
ffmpeg7:7.1.1-1 ... 7:9.0.1-1 (23 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
ffmpeg7:7.1.1-1 ... 7:9.0.1-1 (19 versions)——

Weakness Classification(1)

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

All Vendor Advisories

(2)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 20× in last 7d / 79× 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.

Showing the most recent 100 of 150 total refreshes for this CVE.

  1. 2026-09-15 09:35 UTCEG score recompute
  2. 2026-09-15 09:35 UTCVendor advisory
  3. 2026-09-15 09:35 UTCGHSA enrichment
  4. 2026-09-13 21:46 UTCEG score recompute
  5. 2026-09-13 21:46 UTCVendor advisory
  6. 2026-09-13 21:46 UTCGHSA enrichment
  7. 2026-09-12 19:00 UTCEG score recompute
  8. 2026-09-12 19:00 UTCVendor advisory
  9. 2026-09-12 19:00 UTCGHSA enrichment
  10. 2026-09-11 16:36 UTCEG score recompute
  11. 2026-09-11 16:36 UTCVendor advisory
  12. 2026-09-11 16:36 UTCGHSA enrichment
  13. 2026-09-11 14:53 UTCEPSS rescore
  14. 2026-09-11 09:37 UTCEPSS rescore
  15. 2026-09-10 13:35 UTCEG score recompute
  16. 2026-09-10 13:35 UTCVendor advisory
  17. 2026-09-10 13:35 UTCGHSA enrichment
  18. 2026-09-09 08:44 UTCEG score recompute
  19. 2026-09-09 08:44 UTCVendor advisory
  20. 2026-09-09 08:44 UTCGHSA enrichment
  21. 2026-09-08 22:01 UTCEPSS rescore
  22. 2026-09-07 21:23 UTCEG score recompute
  23. 2026-09-07 21:23 UTCVendor advisory
  24. 2026-09-07 21:23 UTCGHSA enrichment
  25. 2026-09-07 16:01 UTCEPSS rescore
Show 75 more
  1. 2026-09-06 13:47 UTCEPSS rescore
  2. 2026-09-05 19:22 UTCEG score recompute
  3. 2026-09-05 19:22 UTCVendor advisory
  4. 2026-09-05 19:22 UTCGHSA enrichment
  5. 2026-09-05 15:31 UTCEPSS rescore
  6. 2026-09-04 12:48 UTCEG score recompute
  7. 2026-09-04 12:48 UTCGHSA enrichment
  8. 2026-09-04 05:07 UTCEPSS rescore
  9. 2026-09-02 14:12 UTCEPSS rescore
  10. 2026-09-01 23:15 UTCEG score recompute
  11. 2026-09-01 23:15 UTCVendor advisory
  12. 2026-09-01 23:15 UTCGHSA enrichment
  13. 2026-09-01 13:54 UTCEPSS rescore
  14. 2026-09-01 04:40 UTCEPSS rescore
  15. 2026-08-31 02:41 UTCEG score recompute
  16. 2026-08-31 02:41 UTCVendor advisory
  17. 2026-08-31 02:41 UTCGHSA enrichment
  18. 2026-08-30 19:17 UTCEPSS rescore
  19. 2026-08-30 01:22 UTCEPSS rescore
  20. 2026-08-30 00:16 UTCEG score recompute
  21. 2026-08-30 00:16 UTCVendor advisory
  22. 2026-08-30 00:16 UTCGHSA enrichment
  23. 2026-08-28 21:42 UTCEPSS rescore
  24. 2026-08-27 23:45 UTCEG score recompute
  25. 2026-08-27 23:45 UTCVendor advisory
  26. 2026-08-27 23:45 UTCGHSA enrichment
  27. 2026-08-26 21:15 UTCEG score recompute
  28. 2026-08-26 21:15 UTCVendor advisory
  29. 2026-08-26 21:14 UTCGHSA enrichment
  30. 2026-08-26 14:47 UTCEPSS rescore
  31. 2026-08-25 18:22 UTCEG score recompute
  32. 2026-08-25 18:22 UTCVendor advisory
  33. 2026-08-25 18:22 UTCGHSA enrichment
  34. 2026-08-25 13:49 UTCEPSS rescore
  35. 2026-08-24 15:58 UTCEG score recompute
  36. 2026-08-24 15:58 UTCGHSA enrichment
  37. 2026-08-23 13:31 UTCEG score recompute
  38. 2026-08-23 13:31 UTCGHSA enrichment
  39. 2026-08-23 00:19 UTCEPSS rescore
  40. 2026-08-22 11:07 UTCEG score recompute
  41. 2026-08-22 11:07 UTCGHSA enrichment
  42. 2026-08-21 23:49 UTCEPSS rescore
  43. 2026-08-21 08:43 UTCEG score recompute
  44. 2026-08-21 08:43 UTCGHSA enrichment
  45. 2026-08-20 22:56 UTCEPSS rescore
  46. 2026-08-20 06:19 UTCEG score recompute
  47. 2026-08-20 06:19 UTCGHSA enrichment
  48. 2026-08-19 17:04 UTCEPSS rescore
  49. 2026-08-19 03:50 UTCEG score recompute
  50. 2026-08-19 03:50 UTCGHSA enrichment
  51. 2026-08-18 13:48 UTCEPSS rescore
  52. 2026-08-18 01:26 UTCEG score recompute
  53. 2026-08-18 01:26 UTCGHSA enrichment
  54. 2026-08-17 13:47 UTCEPSS rescore
  55. 2026-08-16 22:43 UTCEG score recompute
  56. 2026-08-16 22:43 UTCGHSA enrichment
  57. 2026-08-16 14:56 UTCEPSS rescore
  58. 2026-08-15 20:19 UTCEG score recompute
  59. 2026-08-15 20:19 UTCGHSA enrichment
  60. 2026-08-15 01:30 UTCEPSS rescore
  61. 2026-08-14 17:54 UTCEG score recompute
  62. 2026-08-14 17:54 UTCGHSA enrichment
  63. 2026-08-13 22:00 UTCEPSS rescore
  64. 2026-08-13 15:30 UTCEG score recompute
  65. 2026-08-13 15:30 UTCGHSA enrichment
  66. 2026-08-12 13:51 UTCEPSS rescore
  67. 2026-08-12 12:59 UTCEG score recompute
  68. 2026-08-12 12:59 UTCGHSA enrichment
  69. 2026-08-11 10:35 UTCEG score recompute
  70. 2026-08-11 10:35 UTCGHSA enrichment
  71. 2026-08-11 00:00 UTCEPSS rescore
  72. 2026-08-10 08:10 UTCEG score recompute
  73. 2026-08-10 08:10 UTCGHSA enrichment
  74. 2026-08-09 13:47 UTCEPSS rescore
  75. 2026-08-09 05:47 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-66038?
CVE-2026-66038 is a medium vulnerability published on July 24, 2026. FFmpeg through 8.1.2, fixed in commit 8670835, contains an information disclosure vulnerability in the LCL/ZLIB video decoder that allows attackers to expose uninitialized heap memory by supplying a valid zlib stream that inflates to fewer bytes than the expected frame size. The zlib_decomp()…
When was CVE-2026-66038 disclosed?
CVE-2026-66038 was first published in the National Vulnerability Database on July 24, 2026, with the most recent update on August 7, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-66038 actively exploited?
CVE-2026-66038 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 84.6% of all scored CVEs.
What is the CVSS score of CVE-2026-66038?
CVE-2026-66038 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2026-66038?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-66038, 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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