CVE-2026-27890: Firebird is an open-source relational database management system

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HIGH 8.2REMOTEUPGRADE

CVE-2026-27890 is a high-severity flaw (CVSS 8.2) affecting firebird. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	8.2 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 60%)
CISA exploited list	No
Weakness	CWE-119, CWE-787
Published	2026-04-17
Last modified	2026-10-26

Publisher (CNA): GitHub, Inc. · Vendor: firebirdsql

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-17 19:16 UTCPublished CVE record published
2026-10-26 21:10 UTCUpdated Record last modified

firebirdsql firebird UPGRADE

Affected: < 3.0.14 · >= 4.0.0 and < 4.0.7 · >= 5.0.0 and < 5.0.4

Fixed in: 3.0.14, 4.0.7, 5.0.4

Safe to downgrade to: a release before 4.0.0

1. Check installed version

apt-cache policy firebird || rpm -q firebird || firebird --version

2. UPGRADE to 3.0.14 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade firebird

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade firebird

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 4.0.0 (Debian / Ubuntu)

apt-cache madison firebird sudo apt install firebird=<VERSION_BEFORE_4.0.0> sudo apt-mark hold firebird

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list firebird sudo dnf downgrade firebird-<VERSION_BEFORE_4.0.0> sudo dnf versionlock add firebird

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-27890?

firebird: upgrade to 3.0.14, 4.0.7, 5.0.4. Exact commands for each OS are on this page.

Is CVE-2026-27890 being exploited?

CVE-2026-27890 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-27890 affect?

CVE-2026-27890 affects firebird. Severity is high (CVSS 8.2). 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 orde

How urgent is CVE-2026-27890?

Priority 49/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-40342 CRITICAL 9.9 UPGRADE Firebird is an open-source relational database management system
CVE-2026-35215 HIGH 7.5 UPGRADE Firebird is an open-source relational database management system
CVE-2026-28224 HIGH 8.2 UPGRADE Firebird is an open-source relational database management system
CVE-2026-33337 HIGH 7.5 UPGRADE Firebird is an open-source relational database management system
CVE-2026-28212 HIGH 7.5 UPGRADE Firebird is an open-source relational database management system

References

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