CVE-2026-50259

HIGHPre-NVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

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

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
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

A fix is available — apply it.

A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. _XkbSetMapChecks() declares a fixed-size stack buffer mapWidths[256] indexed by key type index. The helper function CheckKeyTypes() writes to this buffer at a client-controlled offset, allowing a stack buffer overflow. This may be used to crash the server, or for privilege escalation if the X server runs as root.

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
6%
KEV
Not listed

Published

June 5, 2026

Last Modified

July 27, 2026

Advisory Details (5)

Auto-updated Jun 5, 2026
Patch available. Sources: redhat.
generic

Jira

https://redhat.atlassian.net/browse/PSIRTSUPT-16950
generic

X.Org Security Advisory: multiple security issues X.Org X server and Xwayland

https://lists.x.org/archives/xorg-announce/2026-June/003702.html
generic

xkb: clamp nMaps to mapWidths buffer size in CheckKeyTypes (867b59b3) · Commits · xorg / xserver · GitLab

https://gitlab.freedesktop.org/xorg/xserver/-/commit/867b59b33bee669cb412f1314e47c52eacf6e00b
redhat

2485384 – (CVE-2026-50259) CVE-2026-50259 xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: stack buffer overflow in XKB SetMap request via mapWidths indexing

https://bugzilla.redhat.com/show_bug.cgi?id=2485384
redhat Patch Available

cve-details

https://access.redhat.com/security/cve/CVE-2026-50259

Vendor Advisories for CVE-2026-50259(20)

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

Patch Availability(20)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatxorg-x11-server-Xwayland-0:21.1.3-13.el8_8.12026-07-13redhat
redhatxorg-x11-server-Xwayland-0:21.1.3-2.el8_6.72026-07-13redhat
redhatxorg-x11-server-0:1.20.11-19.el8_82026-07-08redhat
redhatxorg-x11-server-0:1.20.11-8.el8_62026-07-08redhat
redhatxorg-x11-server-Xwayland-0:23.2.7-6.el9_6.12026-07-08redhat
redhatxorg-x11-server-Xwayland-0:22.1.9-8.el9_4.12026-07-08redhat
redhatxorg-x11-server-Xwayland-0:24.1.5-6.el10_0.12026-07-08redhat
redhatxorg-x11-server-Xwayland-0:21.1.3-10.el9_2.12026-07-08redhat
redhatxorg-x11-server-0:1.20.10-5.el8_42026-07-08redhat
redhatxorg-x11-server-0:1.20.11-29.el9_42026-07-07redhat
redhatxorg-x11-server-0:1.20.11-21.el9_22026-07-07redhat
redhatxorg-x11-server-0:1.20.11-34.el9_62026-07-07redhat
redhatxorg-x11-server-0:1.20.4-35.el7_92026-07-07redhat
redhattigervnc-0:1.15.0-7.el9_8.22026-06-25redhat
redhattigervnc-0:1.15.0-10.el8_102026-06-24redhat
redhatxorg-x11-server-Xwayland-0:24.1.9-4.el10_2.22026-06-22redhat
redhatxorg-x11-server-0:1.20.11-34.el9_8.22026-06-17redhat
redhatxorg-x11-server-Xwayland-0:24.1.9-4.el9_8.22026-06-17redhat
redhatxorg-x11-server-Xwayland-0:21.1.3-20.el8_10.22026-06-17redhat
redhatxorg-x11-server-0:1.20.11-28.el8_10.22026-06-17redhat

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.

Weakness Classification(1)

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

Additional Vendor Advisories

(5)

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 25× in last 7d / 103× 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 198 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-50259?
CVE-2026-50259 is a high vulnerability published on June 5, 2026. A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. _XkbSetMapChecks() declares a fixed-size stack buffer mapWidths[256] indexed by key type index. The helper function CheckKeyTypes() writes to this buffer at a client-controlled offset, allowing a stack buffer overflow.…
When was CVE-2026-50259 disclosed?
CVE-2026-50259 was first published in the National Vulnerability Database on June 5, 2026, with the most recent update on July 27, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-50259 actively exploited?
CVE-2026-50259 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 93.9% of all scored CVEs.
What is the CVSS score of CVE-2026-50259?
CVE-2026-50259 has a CVSS v3 base score of 7.8 (NVD).
How do I remediate CVE-2026-50259?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-50259, 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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