CVE-2026-76949

Source
https://cve.org/CVERecord?id=CVE-2026-76949
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-76949.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2026-76949
Aliases
Published
2026-09-17T21:57:50Z
Modified
2026-10-22T10:36:15Z
Severity
  • 9.1 (Critical) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N CVSS Calculator
Summary
Remember-me sign-in guard reads a session key that is never written in ash_authentication, allowing session replacement
Details

Authentication Bypass by Spoofing vulnerability in team-alembic ash_authentication allows an attacker who can plant a remember-me cookie in a victim's browser to replace that victim's authenticated session with one for the attacker's own account.

AshAuthentication.Plug.Helpers.sign_in_using_remember_me/3 skips re-authenticating an already-signed-in visitor by checking the session for "<subject_name>_token", but store_in_session/2 writes that key only when require_token_presence_for_authentication? is enabled and otherwise writes the bare subject name. At the default setting the guard therefore reads a key that is never written, its already-signed-in branch is unreachable, and the remember-me sign-in runs on every request through the per-request browser pipeline plug. A planted remember-me cookie is consequently honoured even for a visitor holding a live authenticated session, so whatever the victim enters afterwards lands in data the attacker controls. The read path in authenticate_resource_from_session/4 selects the key correctly, so the guard and the reader disagree about which key holds the session.

This issue affects ash_authentication: from 4.10.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Database specific
{
    "cna_assigner": "EEF",
    "cwe_ids": [
        "CWE-290"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/76xxx/CVE-2026-76949.json"
}
References

Affected packages

Git / github.com/team-alembic/ash_authentication

Affected ranges

Type
GIT
Repo
https://github.com/team-alembic/ash_authentication
Events
Database specific
Show details
{
    "extracted_events": [
        {
            "range": [
                {
                    "introduced": "3d3de314692558d06ec13945f857f00514e95a8c"
                },
                {
                    "fixed": "b9568a53b438247238b1c5a4f49c8d84650f4bba"
                }
            ],
            "source": "AFFECTED_FIELD",
            "strategy": "ChangesAt"
        },
        {
            "range": [
                {
                    "introduced": "4.10.0"
                },
                {
                    "fixed": "4.15.0"
                }
            ],
            "source": "AFFECTED_FIELD",
            "strategy": "StandardRange"
        },
        {
            "range": [
                {
                    "introduced": "5.0.0-rc.0"
                },
                {
                    "fixed": "5.0.0-rc.14"
                }
            ],
            "source": "AFFECTED_FIELD",
            "strategy": "StandardRange"
        },
        {
            "range": [
                {
                    "fixed": "3d3de314692558d06ec13945f857f00514e95a8c"
                }
            ],
            "source": "REFERENCES_COMMIT"
        },
        {
            "range": [
                {
                    "fixed": "b9568a53b438247238b1c5a4f49c8d84650f4bba"
                }
            ],
            "source": "REFERENCES_COMMIT"
        },
        {
            "range": [
                {
                    "fixed": "9a34136b844abe179da1075067cf2835c64dcc12"
                }
            ],
            "source": "REFERENCES_COMMIT"
        }
    ]
}

Affected versions

5.*
5.0.0-rc.8
5.0.0-rc.9
v4.*
v4.10.0
v4.11.0
v4.12.0
v4.13.0
v4.13.1
v4.13.2
v4.13.3
v4.13.4
v4.13.5
v4.13.6
v4.13.7
v4.14.0
v4.14.1
v4.14.2
v5.*
v5.0.0-rc.0
v5.0.0-rc.1
v5.0.0-rc.10
v5.0.0-rc.11
v5.0.0-rc.12
v5.0.0-rc.13
v5.0.0-rc.2
v5.0.0-rc.3
v5.0.0-rc.4
v5.0.0-rc.5
v5.0.0-rc.6
v5.0.0-rc.7

Database specific

source
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-76949.json"