CVE-2026-27890

HIGH
Published Apr 17, 2026 Modified Apr 24, 2026 CWE-119 CWE-787

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.

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CVSS v3.1 Score

8.2
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

EPSS — Exploit Prediction

0.0040
Probability of exploitation
0.61%
Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-119 Buffer Overflow
CWE-787 Out-of-bounds Write

Affected Products

Vendor Product
firebirdsql firebird
firebirdsql firebird
firebirdsql firebird

References

Frequently Asked Questions

What is 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. It has a CVSS v3.1 base score of 8.2 (HIGH).
How severe is CVE-2026-27890? +
CVE-2026-27890 has a CVSS v3.1 score of 8.2 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0040, placing it in the 1th percentile for exploitation probability.
What products are affected by CVE-2026-27890? +
CVE-2026-27890 affects products from firebirdsql, specifically: firebird. Check the affected products table above for specific version ranges.
How do I check if I'm vulnerable to CVE-2026-27890? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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