CVE-2026-55999

HIGHNVD 7.88.5▲
EchelonGraph scoreMEDIUM confidence

Score 8.5 from GitHub Security Advisory (severity: HIGH) published 2026-07-08. NVD baseline CVSS 7.8; sources differ by 0.7.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 4 sources updated this week
8.5EG
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.

Local attackers with a X connection able to provide PCX fonts to the X server xorg-server before 21.2.24 and xwayland before 24.1.13 could cause a heap buffer overflow via SetFont due to missing glyph boundary checks.

CVSS v3
7.8
EG Score
8.5(medium)
EG Risk
38(Track)
EG Risk 38/100SSVC: 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
Severity85% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
19%
KEV
Not listed

Published

July 8, 2026

Last Modified

July 9, 2026

Advisory Details (2)

Auto-updated Jul 8, 2026
No patch confirmed yet.
generic

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

https://www.openwall.com/lists/oss-security/2026/07/08/2
generic

glamor: reject fonts with per-glyph metrics exceeding maxbounds (fbf7bac2) · Commits · xorg / xserver · GitLab

https://gitlab.freedesktop.org/xorg/xserver/-/commit/fbf7bac22e2c6bd627fb042742a23318263edae1

Vendor Advisories for CVE-2026-55999(20)

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

Patch Availability(18)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatxorg-x11-server-Xwayland-0:21.1.3-2.el8_6.82026-08-11redhat
redhatxorg-x11-server-Xwayland-0:21.1.3-13.el8_8.22026-08-10redhat
redhatxorg-x11-server-Xwayland-0:21.1.3-10.el9_2.22026-08-10redhat
redhatxorg-x11-server-Xwayland-0:22.1.9-8.el9_4.32026-08-10redhat
redhatxorg-x11-server-Xwayland-0:23.2.7-6.el9_6.32026-08-05redhat
redhatxorg-x11-server-0:1.20.4-36.el7_92026-08-04redhat
redhatxorg-x11-server-0:1.20.11-19.el8_8.12026-08-04redhat
redhatxorg-x11-server-Xwayland-0:24.1.5-6.el10_0.22026-08-04redhat
redhatxorg-x11-server-0:1.20.10-5.el8_4.12026-08-03redhat
redhatxorg-x11-server-0:1.20.11-8.el8_6.12026-08-03redhat
redhatxorg-x11-server-0:1.20.11-21.el9_2.12026-08-03redhat
redhatxorg-x11-server-0:1.20.11-29.el9_4.12026-08-03redhat
redhatxorg-x11-server-0:1.20.11-34.el9_6.12026-08-03redhat
redhatxorg-x11-server-Xwayland-0:21.1.3-20.el8_10.32026-07-13redhat
redhatxorg-x11-server-Xwayland-0:24.1.9-4.el9_8.32026-07-13redhat
redhatxorg-x11-server-Xwayland-0:24.1.9-4.el10_2.32026-07-13redhat
redhatxorg-x11-server-0:1.20.11-28.el8_10.32026-07-13redhat
redhatxorg-x11-server-0:1.20.11-34.el9_8.32026-07-13redhat

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-server2:21.1.10-1 ... 2:21.1.9-1+hurd.1 (40 versions)——
xwayland2:22.1.9-1 ... 2:24.1.9-1 (23 versions)——
Debian:13(2)
PackageVulnerable rangeFixed inDependents
xorg-server2:21.1.16-1.3 ... 2:21.1.23-1 (10 versions)——
xwayland2:24.1.10-1 ... 2:24.1.9-1 (6 versions)——
Debian:14(2)
PackageVulnerable rangeFixed inDependents
xorg-server2:21.1.16-1.3 ... 2:21.1.23-1 (7 versions)——
xwayland2:24.1.10-1 ... 2:24.1.9-1 (6 versions)——
Debian:11(1)
PackageVulnerable rangeFixed inDependents
xorg-server2:1.20.11-1 ... 2:21.1.9-1+hurd.1 (61 versions)——

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 30× in last 7d / 169× 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 259 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-55999?
CVE-2026-55999 is a high vulnerability published on July 8, 2026. Local attackers with a X connection able to provide PCX fonts to the X server xorg-server before 21.2.24 and xwayland before 24.1.13 could cause a heap buffer overflow via SetFont due to missing glyph boundary checks.
When was CVE-2026-55999 disclosed?
CVE-2026-55999 was first published in the National Vulnerability Database on July 8, 2026, with the most recent update on July 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55999 actively exploited?
CVE-2026-55999 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 81.3% of all scored CVEs.
What is the CVSS score of CVE-2026-55999?
CVE-2026-55999 has a CVSS v3 base score of 7.8 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 8.5.
How do I remediate CVE-2026-55999?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55999, 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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