CVE-2020-26243

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 2.6%, top 16% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
7.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 3%CVSS: 7.5Exploit: NoneExposed: 0

A fix is available — apply it.

Nanopb is a small code-size Protocol Buffers implementation. In Nanopb before versions 0.4.4 and 0.3.9.7, decoding specifically formed message can leak memory if dynamic allocation is enabled and an oneof field contains a static submessage that contains a dynamic field, and the message being decoded contains the submessage multiple times. This is rare in normal messages, but it is a concern when untrusted data is parsed. This is fixed in versions 0.3.9.7 and 0.4.4. The following workarounds are available: 1) Set the option no_unions for the oneof field. This will generate fields as separate instead of C union, and avoids triggering the problematic code. 2) Set the type of the submessage field inside oneof to FT_POINTER. This way the whole submessage will be dynamically allocated and the problematic code is not executed. 3) Use an arena allocator for nanopb, to make sure all memory can be released afterwards.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
39(Track)
EG Risk 39/100SSVC: 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
Severity75% × 45%
Exploitation3% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
83.8%
KEV
Not listed

Published

November 25, 2020

Last Modified

November 21, 2024

References (8)

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntunanopb (0.4.1-1ubuntu0.1~esm1) @ focal2026-05-23ubuntu

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

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFixed inDependents
nanopb0.4.0 ... 0.4.4.dev1193 (58 versions)0.4.4—

Weakness Classification(2)

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

All Vendor Advisories

(1)

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 12× in last 7d / 44× 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. 2026-07-23 01:51 UTCEG score recompute
  2. 2026-07-22 22:37 UTCEG score recompute
  3. 2026-07-22 14:05 UTCEPSS rescore
  4. 2026-07-21 15:22 UTCEPSS rescore
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  6. 2026-07-20 17:04 UTCEPSS rescore
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  12. 2026-07-16 16:59 UTCEPSS rescore
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  15. 2026-07-15 01:57 UTCEPSS rescore
  16. 2026-07-13 22:27 UTCEPSS rescore
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  18. 2026-07-13 06:10 UTCEPSS rescore
  19. 2026-07-13 06:10 UTCEPSS rescore
  20. 2026-07-12 22:38 UTCOSV refresh
  21. 2026-07-12 05:44 UTCEPSS rescore
  22. 2026-07-11 08:25 UTCEPSS rescore
  23. 2026-07-11 08:25 UTCEPSS rescore
  24. 2026-07-09 19:07 UTCEPSS rescore
  25. 2026-07-08 15:12 UTCEPSS rescore
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  1. 2026-07-07 13:43 UTCEPSS rescore
  2. 2026-07-06 16:25 UTCEPSS rescore
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  4. 2026-07-06 02:21 UTCEPSS rescore
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  6. 2026-07-04 06:29 UTCEPSS rescore
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  8. 2026-06-30 23:20 UTCEPSS rescore
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  10. 2026-06-28 04:54 UTCEPSS rescore
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  12. 2026-06-27 03:06 UTCEPSS rescore
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  14. 2026-06-25 13:48 UTCEPSS rescore
  15. 2026-06-24 14:03 UTCEPSS rescore
  16. 2026-06-24 14:03 UTCEPSS rescore
  17. 2026-06-24 08:29 UTCOSV refresh
  18. 2026-06-23 21:31 UTCEPSS rescore
  19. 2026-06-23 21:31 UTCEPSS rescore
  20. 2026-06-21 14:54 UTCEPSS rescore
  21. 2026-06-21 14:54 UTCEPSS rescore
  22. 2026-06-21 01:57 UTCEPSS rescore
  23. 2026-06-19 19:24 UTCEPSS rescore
  24. 2026-06-19 19:23 UTCEPSS rescore
  25. 2026-06-18 17:50 UTCEPSS rescore
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  27. 2026-06-17 17:50 UTCEPSS rescore
  28. 2026-06-16 17:50 UTCEPSS rescore
  29. 2026-06-15 17:46 UTCEPSS rescore
  30. 2026-06-14 23:15 UTCEPSS rescore
  31. 2026-06-13 22:58 UTCEPSS rescore
  32. 2026-06-12 23:10 UTCEPSS rescore
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  34. 2026-06-10 22:16 UTCEPSS rescore
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  36. 2026-06-08 14:15 UTCEPSS rescore
  37. 2026-06-07 15:23 UTCEPSS rescore
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  39. 2026-06-07 15:23 UTCEPSS rescore
  40. 2026-06-07 12:29 UTCOSV refresh
  41. 2026-06-06 13:46 UTCEPSS rescore
  42. 2026-06-06 13:45 UTCEPSS rescore
  43. 2026-06-05 22:45 UTCEPSS rescore
  44. 2026-06-05 22:45 UTCEPSS rescore
  45. 2026-06-05 06:08 UTCEPSS rescore
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  47. 2026-06-04 13:10 UTCEPSS rescore
  48. 2026-06-04 13:10 UTCEPSS rescore
  49. 2026-06-02 20:11 UTCEPSS rescore
  50. 2026-06-02 20:11 UTCEPSS rescore
  51. 2026-06-01 13:50 UTCEPSS rescore
  52. 2026-06-01 13:50 UTCEPSS rescore
  53. 2026-05-31 22:29 UTCEPSS rescore
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  55. 2026-05-31 00:15 UTCEPSS rescore
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  57. 2026-05-29 13:42 UTCEPSS rescore
  58. 2026-05-28 13:43 UTCEPSS rescore
  59. 2026-05-28 13:43 UTCEPSS rescore
  60. 2026-05-27 13:39 UTCEPSS rescore
  61. 2026-05-26 13:42 UTCEPSS rescore
  62. 2026-05-26 13:42 UTCEPSS rescore
  63. 2026-05-26 07:17 UTCEPSS rescore
  64. 2026-05-26 07:17 UTCEPSS rescore
  65. 2026-05-24 16:48 UTCEPSS rescore
  66. 2026-05-23 04:52 UTCEG score recompute
  67. 2026-05-23 04:52 UTCVendor advisory

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2020-26243?
CVE-2020-26243 is a high vulnerability published on November 25, 2020. Nanopb is a small code-size Protocol Buffers implementation. In Nanopb before versions 0.4.4 and 0.3.9.7, decoding specifically formed message can leak memory if dynamic allocation is enabled and an oneof field contains a static submessage that contains a dynamic field, and the message being…
When was CVE-2020-26243 disclosed?
CVE-2020-26243 was first published in the National Vulnerability Database on November 25, 2020, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2020-26243 actively exploited?
CVE-2020-26243 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 83.8% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2020-26243?
CVE-2020-26243 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2020-26243?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2020-26243, 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.

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