CVE-2026-34501 — Apache
HIGHCVE-2026-34501 is a high-severity (CVSS 7.5) CWE-122 vulnerability. A fix is available — see the affected versions and patch details below.
Apache Portable Runtime Utility: Heap buffer overflow in APR redis client
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.
- 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-2026-34501.
EPSS Exploitation Probability
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-2026-34501 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 377,333 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.
Description
Heap-based Buffer Overflow vulnerability in Apache Portable Runtime Utility redis client.
This issue affects Apache Portable Runtime Utility: from 1.6.0 through 1.6.3.
Users are recommended to upgrade to version 1.6.4, which fixes the issue.
Detection & mitigation playbook
VulnerabilityDetect
Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`). Because remote code execution targets the running service rather than your application code, O3 also flags the exploit behaviour from runtime telemetry and egress traffic.
Fix
Upgrade the affected component to the fixed release for CVE-2026-34501, or apply your distribution's backported patch — distro builds are often patched at an older version number, so check your vendor's advisory rather than the upstream version alone.
Workarounds
Reduce reachability while you patch: restrict network access to the service to trusted sources, disable or gate the affected component where your deployment allows it, and add a WAF/IPS signature if one exists for CVE-2026-34501. O3's runtime protection blocks the cwe-122 flaw at execution, which holds the line on hosts you cannot patch immediately.
How O3 protects you
O3 detects and blocks CVE-2026-34501 exploitation at runtime with eBPF exploit-chain detection, plus L7 egress monitoring that catches a post-exploitation callback and cuts the attacker's outbound channel.
Tailored to CVE-2026-34501. 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.
The impact of this vulnerability is rated as Moderate. Although the flaw involves a heap buffer overflow and the CVSS base score reflects an unauthenticated network vector, exploitation requires the attacker to control or compromise the Redis server that the application queries. An attacker cannot trigger this…
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 10 | apr-util-0:1.6.3-23.el10_2.1 | RHSA-2026:66392 |
| Red Hat Enterprise Linux 8 | apr-util-0:1.6.1-9.el8_10.1 | RHSA-2026:69113 |
| Red Hat Enterprise Linux 9 | apr-util-0:1.6.1-23.el9_8.1 | RHSA-2026:66341 |
| Red Hat Hardened Images | apr-util-main-1.6.5-1.hum1 | RHSA-2026:58474 |
Frequently Asked Questions
Is CVE-2026-34501 in your dependencies?
O3 Security finds CVE-2026-34501 across dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.