How severe is CVE-2026-58155?

CVE-2026-58155 has a CVSS 3.x base score of 9.3, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity high, and availability none.

Is CVE-2026-58155 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (32nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-58155?

CVE-2026-58155 affects Apache Traffic Server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-58155?

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

When was CVE-2026-58155 published?

CVE-2026-58155 was published on 2026-07-29 and last updated on 2026-08-03.

CVE-2026-58155

CVE-2026-58155 is a critical-severity vulnerability in Apache Traffic Server with a CVSS 3.x base score of 9.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-444.

Key facts

Severity: Critical (CVSS 3.x base score 9.3)
CVSS v4: 9.2
EPSS exploit prediction: 0% (32nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-444
Affected product: Apache Traffic Server
Published: 2026-07-29
Last modified: 2026-08-03

Description

Apache Traffic Server truncates over-long header names, allowing header aliasing, request smuggling, and policy bypass. This issue affects Apache Traffic Server: from 8.0.0 through 8.1.9, from 9.0.0 through 9.2.14, from 10.0.0 through 10.1.3. Users are recommended to upgrade to version 9.2.15 or 10.1.4, which fix the issue.

Frequently asked questions

What is CVE-2026-58155?: Apache Traffic Server truncates over-long header names, allowing header aliasing, request smuggling, and policy bypass. This issue affects Apache Traffic Server: from 8.0.0 through 8.1.9, from 9.0.0 through 9.2.14, from 10.0.0 through 10.1.3. Users are recommended to upgrade to version 9.2.15 or 10.1.4, which fix the issue.
How severe is CVE-2026-58155?: CVE-2026-58155 has a CVSS 3.x base score of 9.3, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity high, and availability none.
Is CVE-2026-58155 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (32nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-58155?: CVE-2026-58155 affects Apache Traffic Server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-58155?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2026-58155 published?: CVE-2026-58155 was published on 2026-07-29 and last updated on 2026-08-03.

References

https://lists.apache.org/thread/5prl9glcm9g2swnq9hqxvnokylm1gr6d

Affected products (1)

cpe:2.3:a:apache:traffic_server:*:*:*:*:*:*:*:*

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