CVSS 9.3 · CRITICAL

CVE-2026-58155Critical Request Smuggling in Apache Traffic Server

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.

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Analysis

Apache Traffic Server (ATS) is vulnerable to critical request smuggling and policy bypass. Attackers can exploit improper header name truncation to bypass security filters or alias headers, potentially compromising the integrity of backend communications.

Relevant roles

BackendCyberSecurityCloudKubernetesDockerLinux

Severity

Score: 9.3(CRITICAL)

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:N

AV: NETWORK

AC: LOW

PR: NONE

UI: NONE

S: CHANGED

C: LOW

I: HIGH

A: NONE

Weakness (CWE): CWE-444

EPSS

Probability of exploitation (next 30 days): 0.0026 (0.3%)

Percentile: 17.8%

EPSS: 2026-07-30

Technical description

Published: 7/29/2026, 9:16:29 AM

Last modified: 7/30/2026, 2:54:03 PM

References

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

How to read this card

Actively exploited

KEV (Known Exploited Vulnerabilities) is CISA's catalog of CVEs confirmed as actively exploited in the real world. If a CVE is on KEV, someone is already using it in attacks.

CVSS 10.0

CVSS 10.0 — the theoretical maximum severity. Remotely exploitable, no privileges required, total impact. Not yet confirmed as exploited in the wild, but patch now. Widely used software only: a 10.0 in a niche plugin does not make it here.

AI-recommended

A language model reviewed the CVE and judged that it affects widely deployed software or common developer tooling. A human on the team approved publication before it landed here.

Impact categories the AI evaluates

widely_deployed_infra — Linux kernel, OpenSSL, glibc, k8s, Docker, nginx, OpenSSH.

popular_dev_tooling — Node.js, Python, Go, React, Next.js, common npm/pip libraries.

common_consumer_software — Chrome, Firefox, Windows, macOS, popular mobile apps.

enterprise_saas — GitHub, GitLab, Atlassian, Salesforce, Cisco, Fortinet, Ivanti.

niche_software — Regional CMSs, hobby tools, rarely used libraries.

not_relevant — Vendor-specific firmware, discontinued software.

EPSS — EPSS (Exploit Prediction Scoring System) by FIRST.org estimates the probability that a CVE will be exploited in the next 30 days. Range is 0 to 1; very fresh CVEs typically score low until evidence accumulates.