CVE-2025-15661

MEDIUMNVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

Score 6.5 from GitHub Security Advisory (severity: HIGH) published 2026-06-18. NVD baseline CVSS 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 6.5Exploit: None knownExposed: 0

A fix is available — apply it.

libssh2 through 1.11.1, fixed in commit 2dae302, contains an out-of-bounds heap read vulnerability in the sftp_symlink() function in src/sftp.c that allows a malicious SSH server or man-in-the-middle attacker to disclose heap memory contents or cause a crash by sending a crafted SSH_FXP_NAME response. Attackers can supply a link_len value larger than the actual packet data in SSH_FXP_NAME responses for SFTP READLINK and REALPATH operations, triggering a heap buffer over-read of up to target_len minus one bytes due to the missing validation of available packet buffer size before the memcpy operation.

CVSS v3
6.5
EG Score
6.5(medium)
EG Risk
30(Track)
EG Risk 30/100SSVC: 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
Severity65% × 45%
Exploitation1% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
49%
KEV
Not listed

Published

June 18, 2026

Last Modified

July 14, 2026

Advisory Details (4)

Auto-updated Jun 18, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit, github_pr.
generic

libssh2 - Heap Buffer Over-read via sftp_symlink() in sftp.c | Advisories | VulnCheck

https://www.vulncheck.com/advisories/libssh2-heap-buffer-over-read-via-sftp-symlink-in-sftp-c
github_pr

Update sftp_symlink to avoid out of bounds read #1705

Fix merged in libssh2/libssh2 PR #1717 on 2025-10-10 — awaiting tagged release

https://github.com/libssh2/libssh2/pull/1717
github_pr

sftp: fix OOB read on READLINK/REALPATH name parsing

Upstream fix in progress (PR #1705 · libssh2/libssh2, state=closed)

https://github.com/libssh2/libssh2/pull/1705
github_commit

commit 2dae3024897e (libssh2/libssh2)

Fix landed in libssh2/libssh2 commit 2dae3024897e — awaiting tagged release

https://github.com/libssh2/libssh2/commit/2dae3024897e1898d389835151f4e9606227721d

Vendor Advisories for CVE-2025-15661(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 (1.11.0-4.1ubuntu0.24.04.2) @ noble2026-08-30ubuntu
redhatlibssh2-main-1.11.1-9.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

(5 across 5 ecosystems)
Alpine:v3.24(1)
PackageVulnerable rangeFixed inDependents
rust—1.96.1-r0—
Debian:11(1)
PackageVulnerable rangeFixed inDependents
libssh21.10.0-1 ... 1.9.0-3 (20 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
libssh21.10.0-31.10.0-3+deb12u1—
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 6× in last 7d / 60× 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 221 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2025-15661?
CVE-2025-15661 is a medium vulnerability published on June 18, 2026. libssh2 through 1.11.1, fixed in commit 2dae302, contains an out-of-bounds heap read vulnerability in the sftpsymlink() function in src/sftp.c that allows a malicious SSH server or man-in-the-middle attacker to disclose heap memory contents or cause a crash by sending a crafted SSHFXPNAME response.…
When was CVE-2025-15661 disclosed?
CVE-2025-15661 was first published in the National Vulnerability Database on June 18, 2026, with the most recent update on July 14, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-15661 actively exploited?
CVE-2025-15661 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 51.0% of all scored CVEs.
What is the CVSS score of CVE-2025-15661?
CVE-2025-15661 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2025-15661?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-15661, 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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