CVE-2026-47203

Authelia is an open-source authentication and authorization server providing two-factor authentication and single sign-on (SSO) for applications via a web portal. In versions 4.38.0 through 4.39.19, when a user authenticates via Basic Auth (i.e via the Authorization header with the Basic scheme) on the authz verification endpoint, Authelia takes the username directly from the Authorization header and passes it as is to the regulation system for ban checking and attempt recording. LDAP treats usernames case insensitively : john, John, and JOHN all bind as the same user. But the regulation SQL queries treat the lookup of these values in certain scenarios as case sensitive. This allows each variation of a usernames case to have its own ban bucket. Upgrade to 4.39.20 to receive a patch. As a workaround, explicitly disable the basic auth mechanism.

Authelia is an open-source authentication and authorization server providing two-factor authentication and single sign-on (SSO) for applications via a web portal. In versions 4.38.0 through 4.39.19, when a user authenticates via Basic Auth (i.e via the Authorization header with the Basic scheme) on the authz verification endpoint, Authelia takes the username directly from the Authorization header and passes it as is to the regulation system for ban checking and attempt recording. LDAP treats usernames case insensitively : john, John, and JOHN all bind as the same user. But the regulation SQL queries treat the lookup of these values in certain scenarios as case sensitive. This allows each variation of a usernames case to have its own ban bucket. Upgrade to 4.39.20 to receive a patch. As a workaround, explicitly disable the basic auth mechanism.

Impact

CVSSv4 Baseline Score: Moderate 6.3

CVSSv4 Weighted Score: Low 2.9

The full CVSSv4 Vector for this vulnerability is:

CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P/CR:L/IR:L/AR:L/MAV:N/MAC:H/MAT:N/MPR:N/MUI:N/MVC:L/MVI:N/MVA:N/MSC:N/MSI:N/MSA:N/S:N/AU:Y/R:U/V:D/RE:L/U:Green

CVSSv3.1 Baseline Score: Low 3.7

CVSSv3.1 Overall Score: Medium 4.0

The full CVSSv3.1 Vector equivalent for this vulnerability is:

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N/E:P/RL:O/RC:X/CR:H/IR:L/AR:L/MAV:N/MAC:H/MPR:N/MUI:N/MS:U/MC:L/MI:N/MA:N

The weighted severity rating is a result of no indication this is currently being exploited being available at the time of the publish date, in addition to the fact it's unlikely that it is being exploited currently.

Due to lack of canonicalization of the basic auth username, the effectiveness of the brute force mechanism when using basic auth is partially degraded.

Most passwords of reasonable length are unlikely to have a meaningful effect due to the fact there is no clear feedback to an attacker that is attempting to exploit this, thus their brute force attempts are significantly more likely to miss a valid password than they are identify a valid one.

Details

When a user authenticates via Basic Auth (i.e via the Authorization header with the Basic scheme) on the authz verification endpoint, Authelia takes the username directly from the Authorization header and passes it as is to the regulation system for ban checking and attempt recording.

LDAP treats usernames case insensitively : john, John, and JOHN all bind as the same user. But the regulation SQL queries treat the lookup of these values in certain scenarios as case sensitive. This allows each variation of a usernames case to have its own ban bucket.

Notable conditions or unaffected configurations:

1. The first factor login endpoint (/api/firstfactor) is not affected
2. The LDAP authentication backend must be in use.
3. If the underlying database is case insensitive (as it should be with the collation we use for MySQL) it is not affected
4. Administrators using the recently added IP regulation mode are not affected
5. Administrators using a third-party tool such as CrowdSec or fail2ban are not affected
6. Administrators that have disabled basic auth are not affected

Patches

Upgrade to 4.39.20.

Commit: https://github.com/authelia/authelia/commit/b8985b57b70acdff8f204ed426ff619e763461ad

Workarounds

Explicitly disable the basic auth mechanism.

Caddy, HAProxy, and Traefik

server:
  endpoints:
    authz:
      forward-auth:
        implementation: 'ForwardAuth'
        authn_strategies:
          - name: 'CookieSession'

nginx

server:
  endpoints:
    authz:
      auth-request:
        implementation: 'AuthRequest'
        authn_strategies:
          - name: 'CookieSession'

Envoy

server:
  endpoints:
    authz:
      ext-authz:
        implementation: 'ExtAuthz'
        authn_strategies:
          - name: 'CookieSession'

References

N/A

Authelia is an open-source authentication and authorization server providing two-factor authentication and single sign-on (SSO) for applications via a web portal. In versions 4.38.0 through 4.39.19, when a user authenticates via Basic Auth (i.e via the Authorization header with the Basic scheme) on the authz verification endpoint, Authelia takes the username directly from the Authorization header and passes it as is to the regulation system for ban checking and attempt recording. LDAP treats usernames case insensitively : john, John, and JOHN all bind as the same user. But the regulation SQL queries treat the lookup of these values in certain scenarios as case sensitive. This allows each variation of a usernames case to have its own ban bucket. Upgrade to 4.39.20 to receive a patch. As a workaround, explicitly disable the basic auth mechanism.

Authelia is an open-source authentication and authorization server providing two-factor authentication and single sign-on (SSO) for applications via a web portal. In versions 4.38.0 through 4.39.19, when a user authenticates via Basic Auth (i.e via the Authorization header with the Basic scheme) on the authz verification endpoint, Authelia takes the username directly from the Authorization header and passes it as is to the regulation system for ban checking and attempt recording. LDAP treats usernames case insensitively : john, John, and JOHN all bind as the same user. But the regulation SQL queries treat the lookup of these values in certain scenarios as case sensitive. This allows each variation of a usernames case to have its own ban bucket. Upgrade to 4.39.20 to receive a patch. As a workaround, explicitly disable the basic auth mechanism.

Impact

CVSSv4 Baseline Score: Moderate 6.3

CVSSv4 Weighted Score: Low 2.9

The full CVSSv4 Vector for this vulnerability is:

CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P/CR:L/IR:L/AR:L/MAV:N/MAC:H/MAT:N/MPR:N/MUI:N/MVC:L/MVI:N/MVA:N/MSC:N/MSI:N/MSA:N/S:N/AU:Y/R:U/V:D/RE:L/U:Green

CVSSv3.1 Baseline Score: Low 3.7

CVSSv3.1 Overall Score: Medium 4.0

The full CVSSv3.1 Vector equivalent for this vulnerability is:

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N/E:P/RL:O/RC:X/CR:H/IR:L/AR:L/MAV:N/MAC:H/MPR:N/MUI:N/MS:U/MC:L/MI:N/MA:N

The weighted severity rating is a result of no indication this is currently being exploited being available at the time of the publish date, in addition to the fact it's unlikely that it is being exploited currently.

Due to lack of canonicalization of the basic auth username, the effectiveness of the brute force mechanism when using basic auth is partially degraded.

Most passwords of reasonable length are unlikely to have a meaningful effect due to the fact there is no clear feedback to an attacker that is attempting to exploit this, thus their brute force attempts are significantly more likely to miss a valid password than they are identify a valid one.

Details

When a user authenticates via Basic Auth (i.e via the Authorization header with the Basic scheme) on the authz verification endpoint, Authelia takes the username directly from the Authorization header and passes it as is to the regulation system for ban checking and attempt recording.

LDAP treats usernames case insensitively : john, John, and JOHN all bind as the same user. But the regulation SQL queries treat the lookup of these values in certain scenarios as case sensitive. This allows each variation of a usernames case to have its own ban bucket.

Notable conditions or unaffected configurations:

1. The first factor login endpoint (/api/firstfactor) is not affected
2. The LDAP authentication backend must be in use.
3. If the underlying database is case insensitive (as it should be with the collation we use for MySQL) it is not affected
4. Administrators using the recently added IP regulation mode are not affected
5. Administrators using a third-party tool such as CrowdSec or fail2ban are not affected
6. Administrators that have disabled basic auth are not affected

Patches

Upgrade to 4.39.20.

Commit: https://github.com/authelia/authelia/commit/b8985b57b70acdff8f204ed426ff619e763461ad

Workarounds

Explicitly disable the basic auth mechanism.

Caddy, HAProxy, and Traefik

server:
  endpoints:
    authz:
      forward-auth:
        implementation: 'ForwardAuth'
        authn_strategies:
          - name: 'CookieSession'

nginx

server:
  endpoints:
    authz:
      auth-request:
        implementation: 'AuthRequest'
        authn_strategies:
          - name: 'CookieSession'

Envoy

server:
  endpoints:
    authz:
      ext-authz:
        implementation: 'ExtAuthz'
        authn_strategies:
          - name: 'CookieSession'

References

N/A

Authelia Missing Username Canonicalization in Basic Auth (LDAP) in github.com/authelia/authelia

This update for govulncheck-vulndb fixes the following issues:

• Update to version 0.0.20260723T184607 2026-07-23T18:46:07Z (jsc#PED-11136).

Go CVE Numbering Authority IDs added or updated with aliases:

• GO-2026-4730 CVE-2026-33022 GHSA-cv4x-93xx-wgfj
• GO-2026-4761 CVE-2026-33211 GHSA-j5q5-j9gm-2w5c
• GO-2026-5102 CVE-2026-45021 GHSA-3vcp-chfh-f6r2
• GO-2026-5272 CVE-2026-40938 GHSA-94jr-7pqp-xhcq
• GO-2026-5486 CVE-2026-40924 GHSA-m2cx-gpqf-qf74
• GO-2026-5542 CVE-2026-40090 GHSA-pj97-4p9w-gx3q
• GO-2026-5630 CVE-2026-25542 GHSA-rmx9-2pp3-xhcr
• GO-2026-5643 CVE-2026-40923 GHSA-rx35-6rhx-7858
• GO-2026-5675 CVE-2026-41492 GHSA-vvf7-6rmr-m29q
• GO-2026-5711 CVE-2026-40161 GHSA-wjxp-xrpv-xpff
• GO-2026-5746 CVE-2026-41567 GHSA-x86f-5xw2-fm2r
• GO-2026-5749 CVE-2026-41328 GHSA-x92x-px7w-4gx4
• GO-2026-5837 CVE-2026-44840 GHSA-q2m9-6jp9-c6mc
• GO-2026-5929 CVE-2026-44342 GHSA-26v7-h57m-gh9m
• GO-2026-5930 CVE-2026-33655 GHSA-6qcr-qxgr-m7fv
• GO-2026-5933 GHSA-3g4q-2f67-2gvh
• GO-2026-5934 GHSA-59qp-cfj3-rp64
• GO-2026-5935 GHSA-7856-g3gv-9wq8
• GO-2026-5936 CVE-2026-53552 GHSA-26rh-24rg-j3vv
• GO-2026-5937 CVE-2026-53508 GHSA-2jcc-mxv7-p3f9
• GO-2026-5938 CVE-2026-53553 GHSA-4g5x-hcwm-82jw
• GO-2026-5939 CVE-2026-10517 GHSA-698x-9w2p-7vvp
• GO-2026-5940 CVE-2026-53572 GHSA-6w3m-4hhp-775q
• GO-2026-5941 CVE-2026-53487 GHSA-gvhc-wv3v-7pf8
• GO-2026-5942 CVE-2026-46600
• GO-2026-5944 CVE-2026-50197 GHSA-659f-rgp5-w4wf
• GO-2026-5945 CVE-2026-6815 GHSA-rmxx-v9rj-vpvg
• GO-2026-5946 CVE-2026-52831 GHSA-v5px-423j-pf7p
• GO-2026-5947 CVE-2026-53649 GHSA-xqhv-chqm-fhcc
• GO-2026-5948 CVE-2026-50554 GHSA-588f-fvcv-xhvf
• GO-2026-5949 CVE-2026-50553 GHSA-rqrh-8wpv-x7hh
• GO-2026-5950 CVE-2026-53602 GHSA-339v-266x-79xr
• GO-2026-5951 CVE-2026-10219 GHSA-6jm8-4fhr-5w64
• GO-2026-5952 CVE-2026-49834 GHSA-9vcr-p3rj-q5q6
• GO-2026-5953 CVE-2026-9094 GHSA-c9w5-qp6m-m395
• GO-2026-5956 CVE-2026-55252 GHSA-h5g6-xmh4-hc37
• GO-2026-5957 CVE-2026-54158 GHSA-5xfx-xj4h-5p7r
• GO-2026-5958 CVE-2026-54068 GHSA-gcm7-57gf-953c
• GO-2026-5959 CVE-2026-54072 GHSA-h29v-hj44-q8cv
• GO-2026-5961 CVE-2026-54069 GHSA-hvr9-72v2-fff3
• GO-2026-5962 CVE-2026-54088 GHSA-m93h-4hw7-5qcm
• GO-2026-5963 CVE-2026-54067 GHSA-mvjr-vv3c-w4qv
• GO-2026-5964 CVE-2026-54066 GHSA-p4m3-mgmm-c664
• GO-2026-5965 CVE-2026-54070 GHSA-w7cg-whh7-xp28
• GO-2026-5966 CVE-2026-54089 GHSA-xqp3-jq6g-x3qm
• GO-2026-5967 CVE-2026-50551 GHSA-56mp-4f3v-fgj2
• GO-2026-5968 CVE-2026-54174 GHSA-fpg8-7664-jc5q
• GO-2026-5969 GHSA-g936-7jqj-mwv8
• GO-2026-5970 CVE-2026-56852
• GO-2026-5973 CVE-2026-54250 GHSA-jxr7-mqhw-9p98
• GO-2026-5974 CVE-2026-44300 GHSA-wmj8-9953-vff5
• GO-2026-5975 CVE-2026-50018 GHSA-42j2-w334-qxw7
• GO-2026-5976 CVE-2026-50141 GHSA-g7mm-9vx7-jm7h
• GO-2026-5977 CVE-2026-50013 GHSA-qrh4-p6v4-mrfg
• GO-2026-5978 CVE-2026-50125 GHSA-qw5r-ppcg-f8rj
• GO-2026-5979 CVE-2026-50006 GHSA-xrcf-6jh3-ggvx
• GO-2026-5980 CVE-2026-50158 GHSA-2c7f-fxww-6w6c
• GO-2026-5981 GHSA-mqxv-9rm6-w8qc
• GO-2026-5982 GHSA-pqg7-v6wh-3pfp
• GO-2026-5984 CVE-2026-53604 GHSA-2p2f-px33-4vv5
• GO-2026-5985 GHSA-7rx3-5wx3-5v76
• GO-2026-5986 CVE-2026-61699 GHSA-cm26-5974-52h8
• GO-2026-5987 CVE-2026-55513 GHSA-g4x6-jcvr-9m3g
• GO-2026-5988 CVE-2026-54628 GHSA-hwrq-8wxh-q4xv
• GO-2026-5989 CVE-2026-55512 GHSA-m3cx-mwpg-32jg
• GO-2026-5990 CVE-2026-54629 GHSA-mf78-3rpf-r784
• GO-2026-5991 CVE-2026-53603 GHSA-q4vm-pq3q-8wgq
• GO-2026-5992 CVE-2026-61549 GHSA-qf34-295c-26v8
• GO-2026-5996 CVE-2026-54450 GHSA-pph6-vfjv-vpjw
• GO-2026-5997 CVE-2026-54452 GHSA-xgch-x3mx-cm3c
• GO-2026-5998 CVE-2026-54495 GHSA-398h-7f66-3h4p
• GO-2026-5999 CVE-2026-10814 GHSA-jh6h-v6mp-h22v
• GO-2026-6002 CVE-2026-58196 GHSA-pr64-jmmf-jp54
• GO-2026-6003 CVE-2026-53714 GHSA-22xc-xg2r-9j7v
• GO-2026-6004 CVE-2026-52833 GHSA-3v79-m2cg-89ww
• GO-2026-6005 CVE-2026-53715 GHSA-8fv2-88gg-hm7q
• GO-2026-6006 CVE-2026-53716 GHSA-cxpq-8v7q-cg56 *…