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 — 5 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

August 5, 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(28)

Vendor / EcosystemFixed in / PatchReleasedSource
redhattigervnc-0:1.1.0-25.el6_10.182026-08-03redhat
redhattigervnc-0:1.13.1-8.el9_4.102026-07-27redhat
redhattigervnc-0:1.8.0-36.el7_9.52026-07-27redhat
redhattigervnc-0:1.12.0-6.el8_6.182026-07-27redhat
redhattigervnc-0:1.12.0-14.el9_2.152026-07-27redhat
redhattigervnc-0:1.12.0-15.el8_8.182026-07-27redhat
redhattigervnc-0:1.11.0-8.el8_4.162026-07-27redhat
redhattigervnc-0:1.14.1-11.el9_62026-07-27redhat
redhatxorg-x11-server-Xwayland-0:21.1.3-2.el8_6.72026-07-13redhat
redhatxorg-x11-server-Xwayland-0:21.1.3-13.el8_8.12026-07-13redhat
redhatxorg-x11-server-Xwayland-0:23.2.7-6.el9_6.12026-07-08redhat
redhatxorg-x11-server-0:1.20.10-5.el8_42026-07-08redhat
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-0:22.1.9-8.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-0:1.20.11-29.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.

Affected Packages

(7 across 4 ecosystems)
Debian:12(2)
PackageVulnerable rangeFixed inDependents
xorg-server2:21.1.7-3 ... 2:21.1.7-3+deb12u9 (13 versions)2:21.1.7-3+deb12u13—
xwayland2:22.1.9-1 ... 2:24.1.9-1 (24 versions)——
Debian:13(2)
PackageVulnerable rangeFixed inDependents
xorg-server2:21.1.16-1.3, 2:21.1.16-1.3+deb13u1, 2:21.1.16-1.3+deb13u22:21.1.16-1.3+deb13u3—
xwayland2:24.1.10-1 ... 2:24.1.9-1 (7 versions)——
Debian:14(2)
PackageVulnerable rangeFixed inDependents
xorg-server2:21.1.16-1.3 ... 2:21.1.22-1 (6 versions)2:21.1.23-1—
xwayland2:24.1.10-1, 2:24.1.11-1, 2:24.1.6-1, 2:24.1.8-1, 2:24.1.9-12:24.1.12-1—
Debian:11(1)
PackageVulnerable rangeFixed inDependents
xorg-server2:1.20.11-1 ... 2:21.1.9-1+hurd.1 (62 versions)——

Weakness Classification(1)

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

Additional Vendor Advisories

(7)

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 7× in last 7d / 50× 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 374 total refreshes for this CVE.

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

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 August 5, 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 94.0% 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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