CVE-2026-86688

HIGHPre-NVD 7.47.4—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.4 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 65% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 3 sources updated this week
7.4EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.4Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Session Fixation vulnerability in team-alembic ash_authentication allows an attacker who can plant a session identifier in a victim's browser to hold an authenticated session once that victim signs in.

AshAuthentication.Plug.Helpers.store_in_session/2 writes the authenticated subject into the existing session with Plug.Conn.put_session/3 and never calls Plug.Conn.configure_session(renew: true), so the identifier the visitor arrived with carries into their authenticated session. Every authentication event reaches this one function: the default success/4 injected by AshAuthentication.Phoenix.Controller.__using__/1, the AuthController emitted by mix ash_authentication_phoenix.install, and remember-me auto-login. AshAuthentication.Phoenix.Plug.store_in_session/2 is a defdelegate to it. Logout does not close the window either, because clear_session/2 ends with Plug.Conn.clear_session/1, which clears session contents but leaves the identifier intact, so a planted identifier survives a logout-then-login cycle.

This issue affects ash_authentication: from 0.2.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

CVSS v3
7.4
EG Score
7.4(medium)
EG Risk
33(Track)
EG Risk 33/100SSVC: 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
Severity74% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
35%
KEV
Not listed

Published

September 17, 2026

Last Modified

September 18, 2026

Advisory Details (6)

Auto-updated Sep 17, 2026
Patch available. Sources: github_commit, github.
generic

OSV - Open Source Vulnerabilities

https://osv.dev/vulnerability/EEF-CVE-2026-86688
github Patch Available

Session id is not renewed on authentication, allowing session fixation · Advisory · team-alembic/ash_authentication · GitHub

https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-v577-944g-7h3x
github_commit Patch Available

commit a939dde9b917 (team-alembic/ash_authentication)

Patch available: team-alembic/ash_authentication v4.9.7 (contains commit a939dde9b917)

https://github.com/team-alembic/ash_authentication/commit/a939dde9b917c072cdf10c4b0913a9886a4b0231
github_commit Patch Available

commit 872db454405e (team-alembic/ash_authentication)

Patch available: team-alembic/ash_authentication v5.0.0-rc.14 (contains commit 872db454405e)

https://github.com/team-alembic/ash_authentication/commit/872db454405ecad4fcdabd9ff3d8755d1d6a69ae
github_commit Patch Available

commit 3e1d452cbf15 (team-alembic/ash_authentication)

Patch available: team-alembic/ash_authentication v4.15.0 (contains commit 3e1d452cbf15)

https://github.com/team-alembic/ash_authentication/commit/3e1d452cbf1564e87f5f97be882b66fe25af7cfa
generic

CVE-2026-86688

https://cna.erlef.org/cves/CVE-2026-86688.html

Affected Packages

(1 across 1 ecosystem)
Hex(1)
PackageVulnerable rangeFixed inDependents
ash_authentication3.0.3 ... 5.0.0-rc.9 (168 versions)5.0.0-rc.14—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 8× 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.

  1. 2026-09-19 18:01 UTCEG score recompute
  2. 2026-09-19 06:13 UTCEG score recompute
  3. 2026-09-18 19:28 UTCEPSS rescore
  4. 2026-09-18 15:23 UTCEG score recompute
  5. 2026-09-18 14:35 UTCEG score recompute
  6. 2026-09-17 22:24 UTCEG score recompute
  7. 2026-09-17 22:09 UTCEG score recompute
  8. 2026-09-17 22:09 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-86688?
CVE-2026-86688 is a high vulnerability published on September 17, 2026. Session Fixation vulnerability in team-alembic ash_authentication allows an attacker who can plant a session identifier in a victim's browser to hold an authenticated session once that victim signs in. AshAuthentication.Plug.Helpers.storeinsession/2 writes the authenticated subject into the…
When was CVE-2026-86688 disclosed?
CVE-2026-86688 was first published in the National Vulnerability Database on September 17, 2026, with the most recent update on September 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-86688 actively exploited?
CVE-2026-86688 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 65.2% of all scored CVEs.
What is the CVSS score of CVE-2026-86688?
CVE-2026-86688 has a CVSS v3 base score of 7.4 (NVD).
How do I remediate CVE-2026-86688?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-86688, 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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