How severe is CVE-2023-39456?

CVE-2023-39456 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2023-39456 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 53% (99th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-39456?

CVE-2023-39456 primarily affects Apache Traffic Server. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2023-39456?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2023-39456 published?

CVE-2023-39456 was published on 2023-10-17 and last updated on 2026-06-17.

CVE-2023-39456

CVE-2023-39456 is a high-severity vulnerability in Apache Traffic Server with a CVSS 3.x base score of 7.5. Its EPSS exploit-prediction score of 53% places it in the 99th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-20.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 53% (99th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Apache Traffic Server
Published: 2023-10-17
Last modified: 2026-06-17

Description

Improper Input Validation vulnerability in Apache Traffic Server with malformed HTTP/2 frames.This issue affects Apache Traffic Server: from 9.0.0 through 9.2.2. Users are recommended to upgrade to version 9.2.3, which fixes the issue.

Frequently asked questions

What is CVE-2023-39456?: Improper Input Validation vulnerability in Apache Traffic Server with malformed HTTP/2 frames.This issue affects Apache Traffic Server: from 9.0.0 through 9.2.2. Users are recommended to upgrade to version 9.2.3, which fixes the issue.
How severe is CVE-2023-39456?: CVE-2023-39456 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2023-39456 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 53% (99th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-39456?: CVE-2023-39456 primarily affects Apache Traffic Server. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2023-39456?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2023-39456 published?: CVE-2023-39456 was published on 2023-10-17 and last updated on 2026-06-17.

References

Affected products (3)

cpe:2.3:a:apache:traffic_server:*:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:37:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:38:*:*:*:*:*:*:*

More vulnerabilities in Apache Traffic Server

CVE-2014-3525 — Critical (CVSS 10.0): Unspecified vulnerability in Apache Traffic Server 3.x through 3.2.5, 4.x before 4.2.1.1, and 5.x before 5.0.1 has…
CVE-2021-43082 — Critical (CVSS 9.8): Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') vulnerability in the stats-over-http plugin of…
CVE-2021-35474 — Critical (CVSS 9.8): Stack-based Buffer Overflow vulnerability in cachekey plugin of Apache Traffic Server. This issue affects Apache…
CVE-2020-1944 — Critical (CVSS 9.8): There is a vulnerability in Apache Traffic Server 6.0.0 to 6.2.3, 7.0.0 to 7.1.8, and 8.0.0 to 8.0.5 with a smuggling…
CVE-2019-17565 — Critical (CVSS 9.8): There is a vulnerability in Apache Traffic Server 6.0.0 to 6.2.3, 7.0.0 to 7.1.8, and 8.0.0 to 8.0.5 with a smuggling…
CVE-2019-17559 — Critical (CVSS 9.8): There is a vulnerability in Apache Traffic Server 6.0.0 to 6.2.3, 7.0.0 to 7.1.8, and 8.0.0 to 8.0.5 with a smuggling…

All CVEs affecting Apache Traffic Server →

Other CWE-20 (Improper Input Validation) vulnerabilities

CVE-2026-48316 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Improper Input Validation vulnerability that could…
CVE-2026-48281 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Improper Input Validation vulnerability that could…
CVE-2026-48277 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Improper Input Validation vulnerability that could…
CVE-2026-48055 — Critical (CVSS 10.0): Streambert is a cross-platform Electron Desktop App to stream and download any video media. In versions 2.4.0 and…
CVE-2026-34910 — Critical (CVSS 10.0): A malicious actor with access to the network could exploit an Improper Input Validation vulnerability found in UniFi OS…
CVE-2026-33587 — Critical (CVSS 10.0): Lack of user input sanitisation in Open Notebook v1.8.3 allows the application user to execute Python code (and…

Browse all CWE-20 (Improper Input Validation) vulnerabilities →