CVE-2025-15661

MEDIUMNVD 6.56.5
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to NVD's CVSS score.

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, GitHub Security Advisory, NVD CVSS v3

Also known asEUVD-2025-210285 (ENISA EUVD) · GHSA-3wqh-87fg-ffgg (GitHub Security Advisories)Source: ENISA EUVD

6.5EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.6%CVSS: 6.5Exploit: None knownExposed services: Not assessed

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
6.5MEDIUMmedium confidence
EG Risk
30
EG Risk 30/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity65% × 45%
Impact severity (EG Severity): CVSS 6.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.7% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.6%
EPSS %ILE
51st
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (6.5): severity, escalated by confirmed exploitation. This CVE's 6.5 is its impact severity (EG Severity), not escalated.

EG Severity
6.5 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.6% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-10). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

June 18, 2026

Last Modified

November 10, 2026

Advisory Details (4)

Auto-updated Jun 18, 2026
Patch available. Sources: github_commit, github_pr.
Web page

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 pull request

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 pull request

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 / EcosystemFix (by version range) / PatchReleasedSource
ubuntulibssh2-1t64 (1.11.0-4.1ubuntu0.24.04.2) @ noble2026-10-24ubuntu
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

(10 across 8 ecosystems)
Alpine:v3.24(3)
PackageVulnerable rangeFix by version rangeDependents
chromium-rust—
  • every version up to 1.96.1-r0: fixed in 1.96.1-r0
—
libssh2—
  • every version up to 1.11.1-r4: fixed in 1.11.1-r4
—
rust—
  • every version up to 1.96.1-r0: fixed in 1.96.1-r0
—
Alpine:v3.21(1)
PackageVulnerable rangeFix by version rangeDependents
libssh2—
  • every version up to 1.11.1-r3: fixed in 1.11.1-r3
—
Alpine:v3.22(1)
PackageVulnerable rangeFix by version rangeDependents
libssh2—
  • every version up to 1.11.1-r3: fixed in 1.11.1-r3
—
Alpine:v3.23(1)
PackageVulnerable rangeFix by version rangeDependents
libssh2—
  • every version up to 1.11.1-r4: fixed in 1.11.1-r4
—
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
libssh21.10.0-1 ... 1.9.0-3 (20 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
libssh21.10.0-3
  • every version up to 1.10.0-3+deb12u1: fixed in 1.10.0-3+deb12u1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
libssh21.11.1-1
  • every version up to 1.11.1-1+deb13u1: fixed in 1.11.1-1+deb13u1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
libssh21.11.1-1, 1.11.1-2, 1.11.1-3
  • every version up to 1.11.1-4: fixed in 1.11.1-4
—

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 13× in last 7d / 38× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed its CVE.org record (CNA or CISA ADP). An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 308 rows on record for this CVE, as 98 entries (2 repeats merged).

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 2 repeat rows among the latest 100 are merged into the row they repeat. The 208 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-13 16:49 UTCEPSS rescoreEPSS 0.6% · 51st percentile
  2. 2026-11-12 16:32 UTCEPSS rescoreEPSS 0.6% · 51st percentile
  3. 2026-11-11 16:35 UTCEPSS rescoreEPSS 0.6% · 51st percentile
  4. 2026-11-11 05:46 UTCEchelonGraph re-scored
  5. 2026-11-11 05:46 UTCGHSA enrichmentGHSA-3wqh-87fg-ffgg · GitHub severity HIGH · GitHub CVSS 6.5
  6. 2026-11-10 16:39 UTCEPSS rescoreEPSS 0.6% · 51st percentile
  7. 2026-11-10 13:30 UTCVendor advisory
  8. 2026-11-10 13:30 UTCGHSA enrichmentGHSA-3wqh-87fg-ffgg · GitHub severity HIGH · GitHub CVSS 6.5
  9. 2026-11-10 12:42 UTCEchelonGraph re-scored
  10. 2026-11-10 12:42 UTCGHSA enrichmentGHSA-3wqh-87fg-ffgg · GitHub severity HIGH · GitHub CVSS 6.5
  11. 2026-11-09 16:32 UTCEPSS rescoreEPSS 0.6% · 51st percentile
  12. 2026-11-08 16:36 UTCEPSS rescoreEPSS 0.6% · 51st percentile
  13. 2026-11-08 14:07 UTCEchelonGraph re-scored
  14. 2026-11-08 14:07 UTCVendor advisory
  15. 2026-11-08 14:07 UTCGHSA enrichmentGHSA-3wqh-87fg-ffgg · GitHub severity HIGH · GitHub CVSS 6.5
  16. 2026-11-07 16:36 UTCEPSS rescoreEPSS 0.6% · 51st percentile
  17. 2026-11-06 16:33 UTCEPSS rescoreEPSS 0.6% · 51st percentile
  18. 2026-11-05 16:35 UTCEPSS rescoreEPSS 0.6% · 51st percentile
  19. 2026-11-04 16:32 UTCEPSS rescoreEPSS 0.6% · 51st percentile
  20. 2026-11-03 16:44 UTCEPSS rescoreEPSS 0.6% · 51st percentile
  21. 2026-11-02 16:42 UTCEPSS rescoreEPSS 0.6% · 51st percentile
  22. 2026-11-01 16:32 UTCEPSS rescoreEPSS 0.6% · 51st percentile
  23. 2026-10-31 16:30 UTCEPSS rescoreEPSS 0.6% · 51st percentile
  24. 2026-10-30 16:32 UTCEPSS rescoreEPSS 0.6% · 51st percentile
  25. 2026-10-29 16:31 UTCEPSS rescoreEPSS 0.6% · 50th percentile
Show 73 more
  1. 2026-10-28 16:30 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  2. 2026-10-27 16:30 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  3. 2026-10-26 16:29 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  4. 2026-10-25 16:44 UTCEchelonGraph re-scored
  5. 2026-10-25 16:31 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  6. 2026-10-24 16:30 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  7. 2026-10-24 01:31 UTCEchelonGraph re-scored
  8. 2026-10-24 01:31 UTCVendor advisory
  9. 2026-10-24 01:31 UTCGHSA enrichmentGHSA-3wqh-87fg-ffgg · GitHub severity HIGH · GitHub CVSS 6.5
  10. 2026-10-23 16:30 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  11. 2026-10-22 16:32 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  12. 2026-10-21 16:30 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  13. 2026-10-20 16:31 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  14. 2026-10-19 16:30 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  15. 2026-10-18 16:30 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  16. 2026-10-18 05:48 UTCEchelonGraph re-scored
  17. 2026-10-17 16:32 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  18. 2026-10-16 16:37 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  19. 2026-10-15 16:30 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  20. 2026-10-14 16:31 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  21. 2026-10-13 16:31 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  22. 2026-10-12 22:28 UTCVendor advisory
  23. 2026-10-12 22:28 UTCGHSA enrichmentGHSA-3wqh-87fg-ffgg · GitHub severity HIGH · GitHub CVSS 6.5
  24. 2026-10-12 17:22 UTCEchelonGraph re-scored
  25. 2026-10-12 16:32 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  26. 2026-10-11 20:53 UTCEchelonGraph re-scored
  27. 2026-10-11 19:03 UTCEchelonGraph re-scored
  28. 2026-10-11 15:43 UTCEchelonGraph re-scored
  29. 2026-10-11 13:46 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  30. 2026-10-10 19:58 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  31. 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  32. 2026-10-08 17:08 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  33. 2026-10-07 23:46 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  34. 2026-10-06 15:16 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  35. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  36. 2026-10-05 16:29 UTCEchelonGraph re-scored
  37. 2026-10-05 16:29 UTCVendor advisory
  38. 2026-10-05 16:29 UTCGHSA enrichmentGHSA-3wqh-87fg-ffgg · GitHub severity HIGH · GitHub CVSS 6.5
  39. 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  40. 2026-10-03 14:24 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  41. 2026-10-01 19:48 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  42. 2026-09-30 15:02 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  43. 2026-09-28 13:50 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  44. 2026-09-26 15:57 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  45. 2026-09-24 15:01 UTCEchelonGraph re-scored
  46. 2026-09-24 15:01 UTCVendor advisory
  47. 2026-09-24 15:01 UTCGHSA enrichmentGHSA-3wqh-87fg-ffgg · GitHub severity HIGH · GitHub CVSS 6.5
  48. 2026-09-24 14:02 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  49. 2026-09-23 13:46 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  50. 2026-09-22 14:47 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  51. 2026-09-20 20:14 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  52. 2026-09-18 19:27 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  53. 2026-09-16 14:06 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  54. 2026-09-16 05:13 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  55. 2026-09-15 03:08 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  56. 2026-09-13 16:45 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  57. 2026-09-13 13:53 UTCEchelonGraph re-scored
  58. 2026-09-13 13:53 UTCVendor advisory
  59. 2026-09-13 13:53 UTCGHSA enrichmentGHSA-3wqh-87fg-ffgg · GitHub severity HIGH · GitHub CVSS 6.5
  60. 2026-09-12 14:59 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  61. 2026-09-11 14:51 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  62. 2026-09-11 09:35 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  63. 2026-09-10 09:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  64. 2026-09-08 21:59 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  65. 2026-09-07 16:00 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  66. 2026-09-06 13:46 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  67. 2026-09-04 13:59 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  68. 2026-09-04 05:05 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  69. 2026-09-02 14:10 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  70. 2026-09-01 13:52 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  71. 2026-09-01 04:38 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  72. 2026-08-30 20:54 UTCEchelonGraph re-scored
  73. 2026-08-30 20:54 UTCVendor advisory

Related CVEs(same product + same vendor + same CWE)

Frequently asked(5)

What is CVE-2025-15661?
CVE-2025-15661 is a medium-severity vulnerability; its CVE record was published on June 18, 2026. 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…
When was CVE-2025-15661 made public?
CVE-2025-15661 was made public on October 6, 2025: that is the date its CVE record's CNA, VulnCheck, gives for when the vulnerability was made public. The CVE record itself was published on June 18, 2026. EchelonGraph's copy of the record carries a last-modified date of November 10, 2026; the record at its source may have been updated since.
Is CVE-2025-15661 actively exploited?
CVE-2025-15661 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.6% probability of exploitation in the next 30 days (51st percentile of EPSS-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?
A fix for CVE-2025-15661 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2025-15661 are linked in the Vendor Advisories panel on this page.

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