The attemptAuthentication function in Component/Security/Http/Firewall/UsernamePasswordFormAuthenticationListener.php in Symfony before 2.3.41, 2.7.x before 2.7.13, 2.8.x before 2.8.6, and 3.0.x before 3.0.6 does not limit the length of a username stored in a session, which allows remote attackers to cause a denial of service (session storage consumption) via a series of authentication attempts with long, non-existent usernames
Published Jun 1, 2016
7.5
HIGHCVSS 3.0
EPSS 1.86%
Description
The attemptAuthentication function in Component/Security/Http/Firewall/UsernamePasswordFormAuthenticationListener.php in Symfony before 2.3.41, 2.7.x before 2.7.13, 2.8.x before 2.8.6, and 3.0.x before 3.0.6 does not limit the length of a username stored in a session, which allows remote attackers to cause a denial of service (session storage consumption) via a series of authentication attempts with long, non-existent usernames.
Affected products
No data.
Configuration 1
- ≤ 2.3.40
- 2.7.0
- 2.7.1
- 2.7.2
- 2.7.3
- 2.7.4
- 2.7.5
- 2.7.6
- 2.7.7
- 2.7.8
- 2.7.9
- 2.7.10
- 2.7.11
- 2.7.12
- 2.8.0
- 2.8.1
- 2.8.2
- 2.8.3
- 2.8.4
- 2.8.5
- 3.0.0
- 3.0.1
- 3.0.2
- 3.0.3
- 3.0.4
- 3.0.5
Configuration 2
- 8.0
No data.
No Red Hat product state for this CVE.
No package ranges for this CVE.
Remediation
No remediation recorded yet.
Metrics
No CVSS v4.0 score for this CVE.
No CVSS v3.1 score for this CVE.
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
AV:N/AC:L/Au:N/C:N/I:N/A:P
This CVE is not in the KEV list.
No CISA SSVC assessment for this CVE yet.
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
Score over time
2022–2026- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Percentile over time
- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Table of values (12 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 1.86% (0.01862) | 78.49th | v5 (v2026.06.15) |
| Jun 15, 2026 | 1.86% (0.01862) | 76.44th | v5 (v2026.06.15) |
| Mar 30, 2025 | 1.44% (0.01435) | 78.89th | v4 (v2025.03.14) |
| Mar 29, 2025 | 3.33% (0.03330) | 78.60th | v4 (v2025.03.14) |
| Mar 17, 2025 | 1.19% (0.01192) | 77.42th | v4 (v2025.03.14) |
| Dec 12, 2024 | 1.04% (0.01045) | 84.65th | v3 (v2023.03.01) |
| Apr 2, 2024 | 1.04% (0.01045) | 83.68th | v3 (v2023.03.01) |
| Mar 7, 2023 | 1.04% (0.01045) | 81.68th | v3 (v2023.03.01) |
| Mar 6, 2023 | 1.14% (0.01136) | 59.45th | v2 (v2022.01.01) |
| Oct 18, 2022 | 1.14% (0.01136) | 58.28th | v2 (v2022.01.01) |
| Apr 1, 2022 | 1.14% (0.01136) | 56.27th | v2 (v2022.01.01) |
| Feb 4, 2022 | 1.14% (0.01136) | 34.23th | v2 (v2022.01.01) |
References (9)
- http://www.debian.org/security/2016/dsa-3588 vendor-advisoryx_refsource_DEBIAN
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/security-http/CVE-2016-4423.yaml
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/security/CVE-2016-4423.yaml
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2016-4423.yaml
- https://github.com/advisories/GHSA-whgv-8cg3-7hcm Advisory
- https://github.com/symfony/symfony/pull/18733 x_refsource_CONFIRM
- https://nvd.nist.gov/vuln/detail/CVE-2016-4423
- https://symfony.com/blog/cve-2016-4423-large-username-storage-in-session x_refsource_CONFIRMVendor Advisory
- https://symfony.com/cve-2016-4423
Change history (0)
No recorded changes yet.