How severe is CVE-2026-33816?

CVE-2026-33816 has a CVSS score of 9.8/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2026-33816?

CVE-2026-33816 affects the following packages: github.com/jackc/pgx/v5 (Go). Ecosystems affected: Go.

How do I fix CVE-2026-33816?

Update github.com/jackc/pgx/v5 to 5.9.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33816 is resolved across your whole dependency graph.

How do I detect CVE-2026-33816 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/jackc/pgx/v5, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-33816 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2026-33816?

O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-33816 can be triaged on real exposure rather than presence alone.

Is CVE-2026-33816 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-33816 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-33816?

CVE-2026-33816 has an EPSS (Exploit Prediction Scoring System) score of 0.6%, placing it in the 45th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-33816?

CVE-2026-33816 is classified as Out-of-bounds Write (CWE-787). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-33816 published, and has it been updated?

CVE-2026-33816 was published on April 7, 2026 and was last updated on September 12, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹

🐹 Go

Not in CISA KEV

CRITICAL severity

CVE-2026-33816 — v5

CRITICAL

CVE-2026-33816 is a critical-severity (CVSS 9.8) Out-of-bounds Write vulnerability in github.com/jackc/pgx/v5. A fix is available for github.com/jackc/pgx/v5 — see the affected versions and patch details below.

CVE-2026-33816 in github.com/jackc/pgx

Also known asGHSA-9jj7-4m8r-rfcmGO-2026-4772

Published

Apr 7, 2026

Updated

Sep 12, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Sep 19, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
A successful exploit gives an attacker total control of the affected component, not partial access.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-33816.

EPSS Exploitation Probability

via FIRST.org ↗

0.6%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs45th percentile — riskier than 45% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

How urgent is this, really

CVE-2026-33816 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.

Where this sits among everything scored

Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.

Real-World Exposure

1 pkg affected

🐹github.com/jackc/pgx/v5

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Memory-safety vulnerability in github.com/jackc/pgx/v5.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/jackc/pgx/v5`	all versions	5.9.0`go get github.com/jackc/pgx/v5@v5.9.0`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/jackc/pgx/v5, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/jackc/pgx/v5 to 5.9.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33816 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-33816 can be triaged on real exposure rather than presence alone.

Tailored to CVE-2026-33816. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatImportant

Product	Fixed in	Advisory
Cryostat 4 on RHEL 9	`cryostat/cryostat-storage-rhel9:4.2.0-13`	RHSA-2026:17789
Red Hat Enterprise Linux 10	`go-fdo-server-0:1.0.1-1.el10_2`	RHSA-2026:19137
RHEM 1.0 for RHEL 9	`flightctl-0:1.0.3-1.el9em`	RHSA-2026:36796
RHEM 1.1 for RHEL 10	`flightctl-0:1.1.3-1.el10em`	RHSA-2026:41019
Custom Metric Autoscaler 2.19	`custom-metrics-autoscaler/custom-metrics-autoscaler-adapter-rhel9:1780101236`	RHSA-2026:26636
Custom Metric Autoscaler 2.19	`custom-metrics-autoscaler/custom-metrics-autoscaler-adapter-rhel9:1788361753`	RHSA-2026:62866
Multicluster Global Hub 1.3.4	`multicluster-globalhub/multicluster-globalhub-agent-rhel9:1779210675`	RHSA-2026:22423
Multicluster Global Hub 1.7.0	`multicluster-globalhub/multicluster-globalhub-grafana-rhel9:1779925273`	RHSA-2026:24503

Frequently Asked Questions

Memory-safety vulnerability in github.com/jackc/pgx/v5.

O3 Security · Impact-Aware SCA

Is CVE-2026-33816 in your dependencies?

O3 Security finds CVE-2026-33816 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

Scan my dependencies How O3 SCA works