Vulnerability · Published Apr 17, 2026 · Assigned by GitHub_M
CVE-2026-27890Firebird has Pre-Auth DOS when Processing Out of Order CNCT_specific_data Segments
High 8.2
In plain English
A high-severity memory corruption in firebird from FirebirdSQL. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 40% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Firebird is an open-source relational database management system. In versions prior to 5.0.4, 4.0.7 and 3.0.14, when processing CNCT_specific_data segments during authentication, the server assumes segments arrive in strictly ascending order. If segments arrive out of order, the Array class's grow() method computes a negative size value, causing a SIGSEGV crash. An unauthenticated attacker who knows only the server's IP and port can exploit this to crash the server. This issue has been fixed in versions 5.0.4, 4.0.7 and 3.0.14.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | firebird3.0 | no fix listed | DEBIAN-CVE-2026-27890 |
| Debian:13 | firebird3.0 | no fix listed | DEBIAN-CVE-2026-27890 |
| Debian:14 | firebird3.0 | 3.0.14.ds7-1 | DEBIAN-CVE-2026-27890 |
| Debian:13 | firebird4.0 | no fix listed | DEBIAN-CVE-2026-27890 |
| Debian:14 | firebird4.0 | 4.0.7.3271.ds6-1 | DEBIAN-CVE-2026-27890 |
| Ubuntu:22.04:LTS | firebird3.0 | no fix listed | UBUNTU-CVE-2026-27890 |
| Ubuntu:24.04:LTS | firebird3.0 | no fix listed | UBUNTU-CVE-2026-27890 |
| Ubuntu:25.10 | firebird3.0 | no fix listed | UBUNTU-CVE-2026-27890 |
| Ubuntu:26.04:LTS | firebird3.0 | no fix listed | UBUNTU-CVE-2026-27890 |
| Ubuntu:26.10 | firebird3.0 | no fix listed | UBUNTU-CVE-2026-27890 |
| Ubuntu:25.10 | firebird4.0 | no fix listed | UBUNTU-CVE-2026-27890 |
| Ubuntu:26.04:LTS | firebird4.0 | no fix listed | UBUNTU-CVE-2026-27890 |
| Ubuntu:26.10 | firebird4.0 | no fix listed | UBUNTU-CVE-2026-27890 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| FirebirdSQL | firebird | >= 3.0.0, < 3.0.14>= 4.0.0, < 4.0.7>= 5.0.0, < 5.0.4 |
Weakness: CWE-119, CWE-787 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
References
- https://github.com/FirebirdSQL/firebird/security/advisories/GHSA-6crx-4g37-7j49 x_refsource_CONFIRM
- https://github.com/FirebirdSQL/firebird/releases/tag/v3.0.14 x_refsource_MISC
- https://github.com/FirebirdSQL/firebird/releases/tag/v4.0.7 x_refsource_MISC
- https://github.com/FirebirdSQL/firebird/releases/tag/v5.0.4 x_refsource_MISC