Buffer overflow in Firebirdsql Firebird
CVE-2026-27890
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.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.2 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H.
EPSS exploit prediction
EPSS: 0.007 (53.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 53rd percentile — 53.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.007 · change: +0.003
Affected products
- Firebirdsql Firebird — versions >= 3.0.0, < 3.0.14, >= 4.0.0, < 4.0.7, >= 5.0.0, < 5.0.4
Weakness classification (CWE)
References
- github.com/FirebirdSQL/firebird/security/advisories/GHSA-6crx-4g37-7j49 (Exploit, Vendor Advisory)
- github.com/FirebirdSQL/firebird/releases/tag/v3.0.14 (Release Notes)
- github.com/FirebirdSQL/firebird/releases/tag/v4.0.7 (Release Notes)
- github.com/FirebirdSQL/firebird/releases/tag/v5.0.4 (Release Notes)
Frequently asked questions
- What is CVE-2026-27890?
- CVE-2026-27890 is a high-severity vulnerability in Firebirdsql Firebird, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 8.2/10. Published 2026-04-17.
- How severe is CVE-2026-27890?
- High severity. CVSS v3 base score is 8.2 out of 10.