CVE-2026-6691

HIGHPre-NVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2026-05-06. a secondary CVSS source baseline 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
7.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.8Exploit: None knownExposed: 0

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

The MongoDB C Driver's Cyrus SASL integration performs unsafe string copying during username canonicalization, enabling a heap buffer overflow before any authentication or network traffic. This may be triggered by passing untrusted input in the username of a MongoDB URI with authMechanism=GSSAPI.

CVSS v3
7.8
EG Score
7.8(medium)
EG Risk
35(Track)
EG Risk 35/100SSVC: 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
Severity78% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
3%
KEV
Not listed

Published

May 6, 2026

Last Modified

June 18, 2026

Advisory Details (1)

Auto-updated May 6, 2026
No patch confirmed yet.
generic

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https://jira.mongodb.org/browse/CDRIVER-6134

Vendor Advisories for CVE-2026-6691(1)

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

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
mongo-c-driver1.17.6-1 ... 2.3.3-1 (61 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
mongo-c-driver1.23.1-1, 1.23.1-1+deb12u1, 1.23.1-1+deb12u21.23.1-1+deb12u3—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
mongo-c-driver1.30.4-1, 1.30.4-1+deb13u11.30.4-1+deb13u2—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
mongo-c-driver1.30.4-1, 2.0.2-1, 2.1.0-1, 2.1.1-1, 2.1.2-12.2.0-1—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 6× in last 7d / 31× 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 201 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-6691?
CVE-2026-6691 is a high vulnerability published on May 6, 2026. The MongoDB C Driver's Cyrus SASL integration performs unsafe string copying during username canonicalization, enabling a heap buffer overflow before any authentication or network traffic. This may be triggered by passing untrusted input in the username of a MongoDB URI with authMechanism=GSSAPI.
When was CVE-2026-6691 disclosed?
CVE-2026-6691 was first published in the National Vulnerability Database on May 6, 2026, with the most recent update on June 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-6691 actively exploited?
CVE-2026-6691 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 97.4% of all scored CVEs.
What is the CVSS score of CVE-2026-6691?
CVE-2026-6691 has a CVSS v3 base score of 7.8 (NVD).
How do I remediate CVE-2026-6691?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-6691, 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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