CVE-2026-55200

HIGHNVD 8.38.3—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.3 under NVD CVSS v3. EPSS exploit probability: 4.0%, top 10% of all CVEs by exploit prediction. GitHub Security Advisory enrichment pending alignment with NVD CVSS.

Triggered by: NVD CVSS baseline
Sources: epss, ghsa, nvd
Trending — 4 sources updated this weekElevated
8.3EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 4%CVSS: 8.3Exploit: Elevated riskExposed: 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
8.3(medium)
EG Risk
53(Track*)
EG Risk 53/100SSVC: 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
Severity83% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Watch closely — could escalate to Attend.
EPSS PROB
4%
EPSS %ILE
90%
KEV
Not listed

Published

June 17, 2026

Last Modified

September 17, 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) @ resolute2026-09-17ubuntu
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.

Affected Packages

(7 across 6 ecosystems)
Alpine:v3.24(2)
PackageVulnerable rangeFixed inDependents
libssh2—1.11.1-r3—
rust—1.96.1-r0—
Alpine:v3.21(1)
PackageVulnerable rangeFixed inDependents
libssh2—1.11.1-r2—
Alpine:v3.22(1)
PackageVulnerable rangeFixed inDependents
libssh2—1.11.1-r2—
Alpine:v3.23(1)
PackageVulnerable rangeFixed inDependents
libssh2—1.11.1-r3—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
libssh21.11.1-11.11.1-1+deb13u1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
libssh21.11.1-1, 1.11.1-2, 1.11.1-31.11.1-4—

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 15× in last 7d / 53× 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 362 total refreshes for this CVE.

  1. 2026-09-18 19:28 UTCEPSS rescore
  2. 2026-09-17 19:31 UTCEPSS rescore
  3. 2026-09-17 18:16 UTCEG score recompute
  4. 2026-09-17 18:16 UTCVendor advisory
  5. 2026-09-17 18:16 UTCGHSA enrichment
  6. 2026-09-16 14:08 UTCEPSS rescore
  7. 2026-09-16 05:15 UTCEPSS rescore
  8. 2026-09-15 03:11 UTCEPSS rescore
  9. 2026-09-14 02:22 UTCEG score recompute
  10. 2026-09-14 02:22 UTCVendor advisory
  11. 2026-09-14 02:22 UTCGHSA enrichment
  12. 2026-09-13 16:47 UTCEPSS rescore
  13. 2026-09-13 14:07 UTCEG score recompute
  14. 2026-09-13 14:07 UTCVendor advisory
  15. 2026-09-13 14:07 UTCGHSA enrichment
  16. 2026-09-11 14:53 UTCEPSS rescore
  17. 2026-09-10 09:35 UTCEPSS rescore
  18. 2026-09-08 22:01 UTCEPSS rescore
  19. 2026-09-07 16:01 UTCEPSS rescore
  20. 2026-09-06 13:47 UTCEPSS rescore
  21. 2026-09-04 05:06 UTCEPSS rescore
  22. 2026-09-02 14:12 UTCEPSS rescore
  23. 2026-09-01 13:54 UTCEPSS rescore
  24. 2026-09-01 04:40 UTCEPSS rescore
  25. 2026-08-30 21:16 UTCEG score recompute
Show 75 more
  1. 2026-08-30 21:16 UTCVendor advisory
  2. 2026-08-30 21:16 UTCGHSA enrichment
  3. 2026-08-30 19:17 UTCEPSS rescore
  4. 2026-08-30 01:22 UTCEPSS rescore
  5. 2026-08-28 21:41 UTCEPSS rescore
  6. 2026-08-27 14:25 UTCEPSS rescore
  7. 2026-08-26 14:46 UTCEPSS rescore
  8. 2026-08-25 13:49 UTCEPSS rescore
  9. 2026-08-24 22:22 UTCEG score recompute
  10. 2026-08-24 22:22 UTCVendor advisory
  11. 2026-08-24 22:22 UTCGHSA enrichment
  12. 2026-08-24 05:18 UTCVendor advisory
  13. 2026-08-24 05:18 UTCGHSA enrichment
  14. 2026-08-23 14:57 UTCVendor advisory
  15. 2026-08-23 14:57 UTCGHSA enrichment
  16. 2026-08-23 03:52 UTCEG score recompute
  17. 2026-08-23 03:52 UTCVendor advisory
  18. 2026-08-23 03:52 UTCGHSA enrichment
  19. 2026-08-23 00:19 UTCEPSS rescore
  20. 2026-08-21 23:49 UTCEPSS rescore
  21. 2026-08-21 17:37 UTCVendor advisory
  22. 2026-08-21 17:37 UTCGHSA enrichment
  23. 2026-08-21 06:22 UTCEG score recompute
  24. 2026-08-21 06:22 UTCVendor advisory
  25. 2026-08-21 06:22 UTCGHSA enrichment
  26. 2026-08-20 22:55 UTCEPSS rescore
  27. 2026-08-20 19:17 UTCVendor advisory
  28. 2026-08-20 19:17 UTCGHSA enrichment
  29. 2026-08-20 08:11 UTCEG score recompute
  30. 2026-08-20 08:11 UTCVendor advisory
  31. 2026-08-20 08:11 UTCGHSA enrichment
  32. 2026-08-19 17:04 UTCEPSS rescore
  33. 2026-08-19 08:05 UTCEG score recompute
  34. 2026-08-19 08:05 UTCVendor advisory
  35. 2026-08-19 08:05 UTCGHSA enrichment
  36. 2026-08-18 13:48 UTCEPSS rescore
  37. 2026-08-17 13:47 UTCEPSS rescore
  38. 2026-08-17 12:29 UTCVendor advisory
  39. 2026-08-17 12:29 UTCGHSA enrichment
  40. 2026-08-17 00:57 UTCEG score recompute
  41. 2026-08-17 00:57 UTCVendor advisory
  42. 2026-08-17 00:57 UTCGHSA enrichment
  43. 2026-08-16 14:56 UTCEPSS rescore
  44. 2026-08-16 13:51 UTCVendor advisory
  45. 2026-08-16 13:51 UTCGHSA enrichment
  46. 2026-08-16 02:45 UTCEG score recompute
  47. 2026-08-16 02:45 UTCVendor advisory
  48. 2026-08-16 02:45 UTCGHSA enrichment
  49. 2026-08-16 02:14 UTCEPSS rescore
  50. 2026-08-15 15:40 UTCVendor advisory
  51. 2026-08-15 15:40 UTCGHSA enrichment
  52. 2026-08-15 04:35 UTCEG score recompute
  53. 2026-08-15 04:35 UTCVendor advisory
  54. 2026-08-15 04:35 UTCGHSA enrichment
  55. 2026-08-15 01:30 UTCEPSS rescore
  56. 2026-08-14 17:29 UTCVendor advisory
  57. 2026-08-14 17:29 UTCGHSA enrichment
  58. 2026-08-14 06:10 UTCEG score recompute
  59. 2026-08-14 06:10 UTCVendor advisory
  60. 2026-08-14 06:10 UTCGHSA enrichment
  61. 2026-08-13 22:00 UTCEPSS rescore
  62. 2026-08-13 19:04 UTCVendor advisory
  63. 2026-08-13 19:04 UTCGHSA enrichment
  64. 2026-08-13 04:14 UTCVendor advisory
  65. 2026-08-13 04:14 UTCGHSA enrichment
  66. 2026-08-12 17:09 UTCEG score recompute
  67. 2026-08-12 17:09 UTCVendor advisory
  68. 2026-08-12 17:09 UTCGHSA enrichment
  69. 2026-08-12 13:51 UTCEPSS rescore
  70. 2026-08-12 06:01 UTCVendor advisory
  71. 2026-08-12 06:01 UTCGHSA enrichment
  72. 2026-08-11 18:26 UTCEG score recompute
  73. 2026-08-11 18:26 UTCVendor advisory
  74. 2026-08-11 18:25 UTCGHSA enrichment
  75. 2026-08-11 07:17 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 September 17, 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 4% probability of exploitation in the next 30 days, which ranks it in the top 9.9% of all scored CVEs.
What is the CVSS score of CVE-2026-55200?
CVE-2026-55200 has a CVSS v3 base score of 8.3 (NVD).
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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-55200

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