CVE-2026-9521

HIGHNVD 7.37.3—
EchelonGraph scoreMEDIUM confidence

Score 7.3 from GitHub Security Advisory (severity: LOW) published 2026-05-26. NVD baseline CVSS 7.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 3 sources updated this weekElevated
7.3EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.3Exploit: Elevated riskExposed: 0

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

A security vulnerability has been detected in fraillt bitsery up to 5.2.4. Affected is the function loadFromSharedState in the library include/bitsery/ext/std_smart_ptr.h. Such manipulation leads to improper validation of specified type of input. It is possible to launch the attack remotely. The exploit has been disclosed publicly and may be used. Upgrading to version 5.2.5 is able to address this issue. The name of the patch is 66d16516e24893bebc1c8af52bf2fe9ad0735061. Upgrading the affected component is advised.

CVSS v3
7.3
EG Score
7.3(medium)
EG Risk
64(Attend)
EG Risk 64/100SSVC: Attend

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
Severity73% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
0%
EPSS %ILE
33%
KEV
Not listed

Published

May 26, 2026

Last Modified

July 23, 2026

Advisory Details (4)

Auto-updated Jun 11, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit.
github_commit

commit 66d16516e248 (fraillt/bitsery)

Fix landed in fraillt/bitsery commit 66d16516e248 — awaiting tagged release

https://github.com/fraillt/bitsery/commit/66d16516e24893bebc1c8af52bf2fe9ad0735061
generic

bitsery/CHANGELOG.md at master · fraillt/bitsery · GitHub

https://github.com/fraillt/bitsery/blob/master/CHANGELOG.md#525-2025-10-09
generic

GitHub - fraillt/bitsery: Your binary serialization library · GitHub

https://github.com/fraillt/bitsery/
generic

cvd_bitsery_20250830.md · GitHub

https://gist.github.com/TrebledJ/750abc64a826f19dd2d6774724629b71

Vendor Advisories for CVE-2026-9521(1)

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

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 12× 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 192 total refreshes for this CVE.

  1. 2026-08-25 13:49 UTCEPSS rescore
  2. 2026-08-24 14:18 UTCEPSS rescore
  3. 2026-08-23 16:25 UTCEG score recompute
  4. 2026-08-23 16:25 UTCGHSA enrichment
  5. 2026-08-23 00:19 UTCEPSS rescore
  6. 2026-08-21 23:49 UTCEPSS rescore
  7. 2026-08-21 21:32 UTCEG score recompute
  8. 2026-08-21 21:32 UTCGHSA enrichment
  9. 2026-08-20 22:56 UTCEPSS rescore
  10. 2026-08-20 18:21 UTCEG score recompute
  11. 2026-08-20 18:21 UTCGHSA enrichment
  12. 2026-08-19 17:04 UTCEPSS rescore
  13. 2026-08-18 13:49 UTCEPSS rescore
  14. 2026-08-17 13:47 UTCEPSS rescore
  15. 2026-08-17 09:36 UTCGHSA enrichment
  16. 2026-08-16 16:34 UTCEG score recompute
  17. 2026-08-16 16:34 UTCGHSA enrichment
  18. 2026-08-16 14:56 UTCEPSS rescore
  19. 2026-08-16 03:09 UTCEG score recompute
  20. 2026-08-16 03:09 UTCGHSA enrichment
  21. 2026-08-16 02:15 UTCEPSS rescore
  22. 2026-08-15 01:31 UTCEPSS rescore
  23. 2026-08-15 00:06 UTCGHSA enrichment
  24. 2026-08-14 12:56 UTCGHSA enrichment
  25. 2026-08-14 01:45 UTCEG score recompute
Show 75 more
  1. 2026-08-14 01:45 UTCGHSA enrichment
  2. 2026-08-13 22:00 UTCEPSS rescore
  3. 2026-08-13 10:41 UTCGHSA enrichment
  4. 2026-08-12 23:14 UTCEG score recompute
  5. 2026-08-12 23:14 UTCGHSA enrichment
  6. 2026-08-12 13:51 UTCEPSS rescore
  7. 2026-08-12 12:04 UTCGHSA enrichment
  8. 2026-08-12 00:53 UTCEG score recompute
  9. 2026-08-12 00:53 UTCGHSA enrichment
  10. 2026-08-11 13:43 UTCEPSS rescore
  11. 2026-08-11 13:43 UTCGHSA enrichment
  12. 2026-08-11 00:24 UTCEG score recompute
  13. 2026-08-11 00:24 UTCGHSA enrichment
  14. 2026-08-11 00:00 UTCEPSS rescore
  15. 2026-08-10 11:07 UTCGHSA enrichment
  16. 2026-08-09 23:38 UTCEG score recompute
  17. 2026-08-09 23:38 UTCGHSA enrichment
  18. 2026-08-09 13:47 UTCEPSS rescore
  19. 2026-08-09 12:28 UTCGHSA enrichment
  20. 2026-08-09 00:11 UTCEG score recompute
  21. 2026-08-09 00:11 UTCGHSA enrichment
  22. 2026-08-08 16:37 UTCEPSS rescore
  23. 2026-08-08 05:00 UTCGHSA enrichment
  24. 2026-08-07 17:50 UTCEG score recompute
  25. 2026-08-07 17:50 UTCGHSA enrichment
  26. 2026-08-07 16:30 UTCEPSS rescore
  27. 2026-08-07 06:39 UTCGHSA enrichment
  28. 2026-08-06 19:28 UTCEG score recompute
  29. 2026-08-06 19:28 UTCGHSA enrichment
  30. 2026-08-06 13:47 UTCEPSS rescore
  31. 2026-08-06 08:18 UTCGHSA enrichment
  32. 2026-08-05 21:05 UTCEG score recompute
  33. 2026-08-05 21:05 UTCGHSA enrichment
  34. 2026-08-05 19:17 UTCEPSS rescore
  35. 2026-08-04 15:10 UTCEPSS rescore
  36. 2026-08-04 10:39 UTCEPSS rescore
  37. 2026-08-04 03:53 UTCGHSA enrichment
  38. 2026-08-03 16:42 UTCEG score recompute
  39. 2026-08-03 16:42 UTCGHSA enrichment
  40. 2026-08-03 10:36 UTCEPSS rescore
  41. 2026-08-03 02:34 UTCGHSA enrichment
  42. 2026-08-02 15:23 UTCGHSA enrichment
  43. 2026-08-02 04:13 UTCEG score recompute
  44. 2026-08-02 04:13 UTCGHSA enrichment
  45. 2026-08-02 02:27 UTCEPSS rescore
  46. 2026-08-01 16:47 UTCEG score recompute
  47. 2026-08-01 16:47 UTCGHSA enrichment
  48. 2026-08-01 04:16 UTCEPSS rescore
  49. 2026-07-30 16:28 UTCEPSS rescore
  50. 2026-07-30 01:30 UTCEPSS rescore
  51. 2026-07-29 17:00 UTCEG score recompute
  52. 2026-07-29 17:00 UTCGHSA enrichment
  53. 2026-07-28 15:37 UTCEPSS rescore
  54. 2026-07-27 14:14 UTCEPSS rescore
  55. 2026-07-26 14:54 UTCEPSS rescore
  56. 2026-07-26 07:55 UTCEG score recompute
  57. 2026-07-26 07:54 UTCGHSA enrichment
  58. 2026-07-25 14:18 UTCEPSS rescore
  59. 2026-07-24 14:18 UTCEPSS rescore
  60. 2026-07-23 11:51 UTCNVD updateCVSS v4 → 2.9
  61. 2026-07-23 03:23 UTCEG score recompute
  62. 2026-07-22 14:08 UTCEPSS rescore
  63. 2026-07-21 15:25 UTCEPSS rescore
  64. 2026-07-21 15:25 UTCEPSS rescore
  65. 2026-07-20 17:08 UTCEPSS rescore
  66. 2026-07-19 14:31 UTCEPSS rescore
  67. 2026-07-19 02:29 UTCEPSS rescore
  68. 2026-07-18 10:04 UTCEPSS rescore
  69. 2026-07-17 17:59 UTCOSV refresh
  70. 2026-07-16 17:03 UTCEPSS rescore
  71. 2026-07-15 16:57 UTCEPSS rescore
  72. 2026-07-15 02:00 UTCEPSS rescore
  73. 2026-07-13 22:31 UTCEPSS rescore
  74. 2026-07-13 06:13 UTCEPSS rescore
  75. 2026-07-12 05:46 UTCEPSS rescore

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-9521?
CVE-2026-9521 is a high vulnerability published on May 26, 2026. A security vulnerability has been detected in fraillt bitsery up to 5.2.4. Affected is the function loadFromSharedState in the library include/bitsery/ext/stdsmartptr.h. Such manipulation leads to improper validation of specified type of input. It is possible to launch the attack remotely. The…
When was CVE-2026-9521 disclosed?
CVE-2026-9521 was first published in the National Vulnerability Database on May 26, 2026, with the most recent update on July 23, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-9521 actively exploited?
CVE-2026-9521 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 67.0% of all scored CVEs.
What is the CVSS score of CVE-2026-9521?
CVE-2026-9521 has a CVSS v3 base score of 7.3 (NVD).
How do I remediate CVE-2026-9521?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-9521, 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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