CVE-2026-40356

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.6%, top 54% of all CVEs by exploit prediction. GitHub Security Advisory enrichment pending alignment with NVD CVSS.

Triggered by: NVD CVSS baseline
Sources: epss, ghsa, nvd
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 7.5Exploit: None knownExposed: 0

A fix is available — apply it.

In MIT Kerberos 5 (aka krb5) before 1.22.3, there is an integer underflow and resultant out-of-bounds read if an application calls gss_accept_sec_context() on a system with a NegoEx mechanism registered in /etc/gss/mech. An unauthenticated remote attacker can trigger this, possibly causing the process to terminate in parse_message.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
34(Track)
EG Risk 34/100SSVC: 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%
Exploitation1% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
46%
KEV
Not listed

Published

April 28, 2026

Last Modified

July 8, 2026

Advisory Details (3)

Auto-updated Jun 14, 2026
🔬 Proof of concept available. Upstream fix merged — awaiting tagged release. Sources: github_commit.
generic

Kerberos Security Advisories

https://web.mit.edu/kerberos/advisories/
github_commit

commit 2e75f0d9362f (krb5/krb5)

Fix landed in krb5/krb5 commit 2e75f0d9362f — awaiting tagged release

https://github.com/krb5/krb5/commit/2e75f0d9362fb979f5fc92829431a590a130929f
generic🟡 PoC Available

Advisory - Kerberos (krb5) Two Unauthenticated Network Vulnerabilities: CVE-2026-40355 & CVE-2026-40356 | Cem’s Blog

https://cems.fun/2026/04/27/krb5-two-unauthenticated-network-vulnerabilities.html

Vendor Advisories for CVE-2026-40356(13)

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

Patch Availability(11)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatoadp/oadp-velero-rhel9:17840588222026-07-22redhat
redhatdiscovery/discovery-ui-rhel9:17821669522026-06-24redhat
redhatkrb5-0:1.21.1-8.el9_6.22026-06-09redhat
redhatkrb5-0:1.20.1-9.el9_2.62026-06-09redhat
redhatkrb5-0:1.21.1-2.el9_4.52026-06-09redhat
redhatinsights-proxy/insights-proxy-container-rhel9:17804204282026-06-02redhat
redhatrhui5/rhua-rhel9:17797982222026-05-27redhat
redhatkrb5-0:1.21.1-10.el9_82026-05-19redhat
redhatkrb5-0:1.21.3-10.el10_22026-05-19redhat
redhatkrb5-0:1.18.2-34.el8_102026-05-13redhat
redhatkrb5-main-1.22.2-7.hum12026-04-30redhat

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
krb51.18.3-6 ... 1.18.3-6+deb11u7 (8 versions)1.18.3-6+deb11u8—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
krb51.20.1-2, 1.20.1-2+deb12u1, 1.20.1-2+deb12u2, 1.20.1-2+deb12u3, 1.20.1-2+deb12u41.20.1-2+deb12u5—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
krb51.21.3-51.21.3-5+deb13u1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
krb51.21.3-5, 1.22.1-1, 1.22.1-21.22.1-2.1—

Weakness Classification(1)

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

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 5× in last 7d / 77× 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 200 total refreshes for this CVE.

  1. 2026-08-25 13:49 UTCEPSS rescore
  2. 2026-08-23 00:19 UTCEPSS rescore
  3. 2026-08-21 23:49 UTCEPSS rescore
  4. 2026-08-20 22:55 UTCEPSS rescore
  5. 2026-08-19 17:03 UTCEPSS rescore
  6. 2026-08-18 13:48 UTCEPSS rescore
  7. 2026-08-17 13:59 UTCEG score recompute
  8. 2026-08-17 13:59 UTCVendor advisory
  9. 2026-08-17 13:59 UTCGHSA enrichment
  10. 2026-08-17 13:47 UTCEPSS rescore
  11. 2026-08-16 14:56 UTCEPSS rescore
  12. 2026-08-16 05:35 UTCEG score recompute
  13. 2026-08-16 05:35 UTCVendor advisory
  14. 2026-08-16 05:35 UTCGHSA enrichment
  15. 2026-08-16 02:14 UTCEPSS rescore
  16. 2026-08-15 01:30 UTCEPSS rescore
  17. 2026-08-14 17:00 UTCVendor advisory
  18. 2026-08-14 17:00 UTCGHSA enrichment
  19. 2026-08-14 03:59 UTCEG score recompute
  20. 2026-08-14 03:59 UTCVendor advisory
  21. 2026-08-14 03:59 UTCGHSA enrichment
  22. 2026-08-13 22:00 UTCEPSS rescore
  23. 2026-08-13 08:25 UTCVendor advisory
  24. 2026-08-13 08:25 UTCGHSA enrichment
  25. 2026-08-12 17:39 UTCEG score recompute
Show 75 more
  1. 2026-08-12 17:39 UTCVendor advisory
  2. 2026-08-12 17:39 UTCGHSA enrichment
  3. 2026-08-12 13:51 UTCEPSS rescore
  4. 2026-08-11 16:38 UTCEG score recompute
  5. 2026-08-11 16:38 UTCVendor advisory
  6. 2026-08-11 16:38 UTCGHSA enrichment
  7. 2026-08-11 13:43 UTCEPSS rescore
  8. 2026-08-11 01:59 UTCEG score recompute
  9. 2026-08-11 01:59 UTCVendor advisory
  10. 2026-08-11 01:59 UTCGHSA enrichment
  11. 2026-08-11 00:00 UTCEPSS rescore
  12. 2026-08-10 04:27 UTCVendor advisory
  13. 2026-08-10 04:27 UTCGHSA enrichment
  14. 2026-08-09 15:48 UTCEG score recompute
  15. 2026-08-09 15:48 UTCVendor advisory
  16. 2026-08-09 15:48 UTCGHSA enrichment
  17. 2026-08-09 13:46 UTCEPSS rescore
  18. 2026-08-09 03:09 UTCEG score recompute
  19. 2026-08-09 03:09 UTCVendor advisory
  20. 2026-08-09 03:09 UTCGHSA enrichment
  21. 2026-08-08 16:37 UTCEPSS rescore
  22. 2026-08-08 05:24 UTCVendor advisory
  23. 2026-08-08 05:24 UTCGHSA enrichment
  24. 2026-08-07 16:45 UTCEG score recompute
  25. 2026-08-07 16:45 UTCVendor advisory
  26. 2026-08-07 16:45 UTCGHSA enrichment
  27. 2026-08-07 04:06 UTCEG score recompute
  28. 2026-08-07 04:06 UTCVendor advisory
  29. 2026-08-07 04:06 UTCGHSA enrichment
  30. 2026-08-06 13:46 UTCEPSS rescore
  31. 2026-08-06 11:27 UTCVendor advisory
  32. 2026-08-06 11:27 UTCGHSA enrichment
  33. 2026-08-05 22:47 UTCEG score recompute
  34. 2026-08-05 22:47 UTCVendor advisory
  35. 2026-08-05 22:47 UTCGHSA enrichment
  36. 2026-08-05 19:17 UTCEPSS rescore
  37. 2026-08-04 15:10 UTCEPSS rescore
  38. 2026-08-04 10:38 UTCEPSS rescore
  39. 2026-08-03 20:50 UTCEG score recompute
  40. 2026-08-03 20:50 UTCVendor advisory
  41. 2026-08-03 20:50 UTCGHSA enrichment
  42. 2026-08-03 10:36 UTCEPSS rescore
  43. 2026-08-02 18:41 UTCVendor advisory
  44. 2026-08-02 18:41 UTCGHSA enrichment
  45. 2026-08-02 06:02 UTCEG score recompute
  46. 2026-08-02 06:02 UTCVendor advisory
  47. 2026-08-02 06:02 UTCGHSA enrichment
  48. 2026-08-02 02:27 UTCEPSS rescore
  49. 2026-08-01 04:16 UTCEPSS rescore
  50. 2026-07-30 16:28 UTCEPSS rescore
  51. 2026-07-30 01:30 UTCEPSS rescore
  52. 2026-07-27 14:13 UTCEPSS rescore
  53. 2026-07-26 14:54 UTCEPSS rescore
  54. 2026-07-26 14:54 UTCEPSS rescore
  55. 2026-07-25 14:18 UTCEPSS rescore
  56. 2026-07-25 14:18 UTCEPSS rescore
  57. 2026-07-24 14:17 UTCEPSS rescore
  58. 2026-07-24 14:17 UTCEPSS rescore
  59. 2026-07-23 14:18 UTCEPSS rescore
  60. 2026-07-23 14:18 UTCEPSS rescore
  61. 2026-07-23 03:11 UTCEG score recompute▲ 1.60
  62. 2026-07-22 14:08 UTCEPSS rescore
  63. 2026-07-21 15:24 UTCEPSS rescore
  64. 2026-07-20 17:08 UTCEPSS rescore
  65. 2026-07-19 20:48 UTCOSV refresh
  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. 2026-07-16 17:03 UTCEPSS rescore
  70. 2026-07-15 16:57 UTCEPSS rescore
  71. 2026-07-15 16:57 UTCEPSS rescore
  72. 2026-07-15 02:00 UTCEPSS rescore
  73. 2026-07-13 22:30 UTCEPSS rescore
  74. 2026-07-13 06:13 UTCEPSS rescore
  75. 2026-07-13 06:13 UTCEPSS rescore

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-40356?
CVE-2026-40356 is a high vulnerability published on April 28, 2026. In MIT Kerberos 5 (aka krb5) before 1.22.3, there is an integer underflow and resultant out-of-bounds read if an application calls gssacceptseccontext() on a system with a NegoEx mechanism registered in /etc/gss/mech. An unauthenticated remote attacker can trigger this, possibly causing the process…
When was CVE-2026-40356 disclosed?
CVE-2026-40356 was first published in the National Vulnerability Database on April 28, 2026, with the most recent update on July 8, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-40356 actively exploited?
CVE-2026-40356 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 53.8% of all scored CVEs.
What is the CVSS score of CVE-2026-40356?
CVE-2026-40356 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-40356?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-40356, 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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-40356

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