CVE-2026-55200

HIGHNVD 8.38.1▼
EchelonGraph scoreHIGH confidence

Score 8.1 from GitHub Security Advisory (severity: CRITICAL) published 2026-06-17. NVD baseline CVSS 8.3; sources differ by 0.2.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 5 sources updated this weekElevated
8.3
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 8.3Exploit: NoneExposed: 0

A fix is available — apply it.

libssh2 through 1.11.1, fixed in commit 7acf3df contains an out-of-bounds write vulnerability in ssh2_transport_read() that fails to enforce upper bounds on packet_length field. Remote attackers can send crafted SSH packets with excessively large packet_length values to corrupt heap memory and achieve remote code execution.

CVSS v3
8.3
EG Score
8.1(high)
EPSS
49.9%
KEV
Not listed

Published

June 17, 2026

Last Modified

July 1, 2026

Advisory Details (5)

Auto-updated Jun 30, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit, github_pr.
generic

exploitarium/libssh2-cve-2026-55200-poc at main · bikini/exploitarium · GitHub

https://web.archive.org/web/20260623211210/https://github.com/bikini/exploitarium/tree/main/libssh2-cve-2026-55200-poc
generic

libssh2 - Out-of-Bounds Write via Unchecked packet_length in transport.c | Advisories | VulnCheck

https://www.vulncheck.com/advisories/libssh2-out-of-bounds-write-via-unchecked-packet-length-in-transport-c
github_pr

transport.c: Additional boundary checks for packet length

Fix merged in libssh2/libssh2 PR #2052 on 2026-06-12 — awaiting tagged release

https://github.com/libssh2/libssh2/pull/2052
github_commit

commit 97acf3dfda80 (libssh2/libssh2)

Fix landed in libssh2/libssh2 commit 97acf3dfda80 — awaiting tagged release

https://github.com/libssh2/libssh2/commit/97acf3dfda80c91c3a8c9f2372546301d4a1a7a8
generic

exploitarium/libssh2-cve-2026-55200-poc at main · bikini/exploitarium · GitHub

https://github.com/bikini/exploitarium/tree/main/libssh2-cve-2026-55200-poc

Vendor Advisories for CVE-2026-55200(3)

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

Patch Availability(2)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulibssh2-1t64 (1.11.1-1ubuntu0.26.04.2) @ resolute2026-07-06ubuntu
redhatlibssh2-main-1.11.1-8.hum12026-06-25redhat

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

(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 56× in last 7d / 139× 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 139 total refreshes for this CVE.

  1. 2026-07-06 22:53 UTCEG score recompute
  2. 2026-07-06 22:53 UTCVendor advisory
  3. 2026-07-06 22:53 UTCGHSA enrichment
  4. 2026-07-06 16:27 UTCEPSS rescore
  5. 2026-07-06 16:27 UTCEPSS rescore
  6. 2026-07-06 11:47 UTCEG score recompute
  7. 2026-07-06 11:47 UTCVendor advisory
  8. 2026-07-06 11:47 UTCGHSA enrichment
  9. 2026-07-06 02:23 UTCEPSS rescore
  10. 2026-07-06 02:23 UTCEPSS rescore
  11. 2026-07-06 00:04 UTCEG score recompute
  12. 2026-07-06 00:04 UTCVendor advisory
  13. 2026-07-06 00:04 UTCGHSA enrichment
  14. 2026-07-05 12:56 UTCEG score recompute
  15. 2026-07-05 12:56 UTCVendor advisory
  16. 2026-07-05 12:56 UTCGHSA enrichment
  17. 2026-07-05 02:31 UTCEPSS rescore
  18. 2026-07-05 02:30 UTCEPSS rescore
  19. 2026-07-05 01:41 UTCEG score recompute
  20. 2026-07-05 01:41 UTCVendor advisory
  21. 2026-07-05 01:41 UTCGHSA enrichment
  22. 2026-07-04 14:32 UTCEG score recompute
  23. 2026-07-04 14:32 UTCVendor advisory
  24. 2026-07-04 14:32 UTCGHSA enrichment
  25. 2026-07-04 06:31 UTCEPSS rescore
Show 75 more
  1. 2026-07-04 06:31 UTCEPSS rescore
  2. 2026-07-04 03:26 UTCEG score recompute
  3. 2026-07-04 03:26 UTCVendor advisory
  4. 2026-07-04 03:25 UTCGHSA enrichment
  5. 2026-07-03 15:05 UTCEG score recompute
  6. 2026-07-03 15:05 UTCVendor advisory
  7. 2026-07-03 15:05 UTCGHSA enrichment
  8. 2026-07-03 03:57 UTCEG score recompute
  9. 2026-07-03 03:57 UTCVendor advisory
  10. 2026-07-03 03:57 UTCGHSA enrichment
  11. 2026-07-02 16:51 UTCEG score recompute
  12. 2026-07-02 16:51 UTCVendor advisory
  13. 2026-07-02 16:51 UTCGHSA enrichment
  14. 2026-07-02 05:45 UTCEG score recompute
  15. 2026-07-02 05:45 UTCVendor advisory
  16. 2026-07-02 05:45 UTCGHSA enrichment
  17. 2026-07-01 18:40 UTCEG score recompute
  18. 2026-07-01 18:40 UTCVendor advisory
  19. 2026-07-01 18:40 UTCGHSA enrichment
  20. 2026-07-01 15:07 UTCEPSS rescore
  21. 2026-07-01 07:35 UTCEG score recompute
  22. 2026-07-01 07:35 UTCVendor advisory
  23. 2026-07-01 07:35 UTCGHSA enrichment
  24. 2026-06-30 23:22 UTCEPSS rescore
  25. 2026-06-30 20:33 UTCNVD updateCVSS v3 → 8.3 · severity → HIGH
  26. 2026-06-30 20:29 UTCEG score recompute
  27. 2026-06-30 20:29 UTCVendor advisory
  28. 2026-06-30 20:29 UTCGHSA enrichment
  29. 2026-06-30 09:24 UTCEG score recompute
  30. 2026-06-30 09:24 UTCVendor advisory
  31. 2026-06-30 09:24 UTCGHSA enrichment
  32. 2026-06-29 22:18 UTCEG score recompute
  33. 2026-06-29 22:18 UTCVendor advisory
  34. 2026-06-29 22:18 UTCGHSA enrichment
  35. 2026-06-29 14:06 UTCEPSS rescore
  36. 2026-06-29 14:06 UTCEPSS rescore
  37. 2026-06-29 11:13 UTCEG score recompute
  38. 2026-06-29 11:13 UTCVendor advisory
  39. 2026-06-29 11:13 UTCGHSA enrichment
  40. 2026-06-29 00:07 UTCEG score recompute
  41. 2026-06-29 00:07 UTCVendor advisory
  42. 2026-06-29 00:07 UTCGHSA enrichment
  43. 2026-06-28 13:02 UTCEG score recompute
  44. 2026-06-28 13:02 UTCVendor advisory
  45. 2026-06-28 13:01 UTCGHSA enrichment
  46. 2026-06-28 04:56 UTCEPSS rescore
  47. 2026-06-28 04:56 UTCEPSS rescore
  48. 2026-06-28 01:56 UTCEG score recompute
  49. 2026-06-28 01:56 UTCVendor advisory
  50. 2026-06-28 01:56 UTCGHSA enrichment
  51. 2026-06-27 14:51 UTCEG score recompute
  52. 2026-06-27 14:51 UTCVendor advisory
  53. 2026-06-27 14:51 UTCGHSA enrichment
  54. 2026-06-27 03:45 UTCEG score recompute
  55. 2026-06-27 03:45 UTCVendor advisory
  56. 2026-06-27 03:45 UTCGHSA enrichment
  57. 2026-06-27 03:08 UTCEPSS rescore
  58. 2026-06-26 19:41 UTCNVD updateCVSS v3 → 9.8 · severity → CRITICAL
  59. 2026-06-26 16:39 UTCEG score recompute
  60. 2026-06-26 16:39 UTCVendor advisory
  61. 2026-06-26 16:39 UTCGHSA enrichment
  62. 2026-06-26 05:34 UTCEG score recompute
  63. 2026-06-26 05:34 UTCVendor advisory
  64. 2026-06-26 05:34 UTCGHSA enrichment
  65. 2026-06-25 18:28 UTCEG score recompute
  66. 2026-06-25 18:28 UTCGHSA enrichment
  67. 2026-06-25 13:49 UTCEPSS rescore
  68. 2026-06-25 07:22 UTCEG score recompute
  69. 2026-06-25 07:22 UTCGHSA enrichment
  70. 2026-06-24 20:14 UTCEG score recompute
  71. 2026-06-24 20:14 UTCGHSA enrichment
  72. 2026-06-24 14:05 UTCEPSS rescore
  73. 2026-06-24 09:04 UTCEG score recompute
  74. 2026-06-24 09:04 UTCGHSA enrichment
  75. 2026-06-23 21:59 UTCEG score recompute

Publicly available exploits

(2 references)

Working exploit code is in the public domain (2 GitHub PoCs). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCxd20111/CVE-2026-55200
    First seen Jun 29, 2026

    CVE-2026-55200 - Critical libssh2 Remote Code Execution Vulnerability

    Open source ↗
  • GitHub PoC0xBlackash/CVE-2026-55200
    First seen Jun 23, 2026

    CVE-2026-55200

    Open source ↗

Frequently asked(5)

What is CVE-2026-55200?
CVE-2026-55200 is a high vulnerability published on June 17, 2026. libssh2 through 1.11.1, fixed in commit 7acf3df contains an out-of-bounds write vulnerability in ssh2transportread() that fails to enforce upper bounds on packetlength field. Remote attackers can send crafted SSH packets with excessively large packetlength values to corrupt heap memory and achieve…
When was CVE-2026-55200 disclosed?
CVE-2026-55200 was first published in the National Vulnerability Database on June 17, 2026, with the most recent update on July 1, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55200 actively exploited?
CVE-2026-55200 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 49.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-55200?
CVE-2026-55200 has a CVSS v3 base score of 8.3 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 8.1.
How do I remediate CVE-2026-55200?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55200, 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

Explore the affected products and dependency analysis for CVE-2026-55200

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