CVE-2026-58436Public exploitNetwork attack vector

Unauthenticated service interruption via quadratic locale parsing

Published Aug 13, 2026 · Updated Aug 13, 2026

Denial of service in Gitea before 1.27.0 allows remote attackers to interrupt the service with a crafted Accept-Language header. The Locale middleware passes the unfiltered header to ParseAcceptLanguage, whose underscore alias bypasses its separator guard and drives quadratic scanning. No authentication or user interaction is required; concurrent requests can consume all CPU cores and leave the HTTP service unavailable.

CVSS severity8.7
High
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Gitea before 1.27.0 allows remote attackers to interrupt the service with a crafted Accept-Language header. The Locale middleware passes the unfiltered header to ParseAcceptLanguage, whose underscore alias bypasses its separator guard and drives quadratic scanning. No authentication or user interaction is required; concurrent requests can consume all CPU cores and leave the HTTP service unavailable.

The record

CVE
CVE-2026-58436
Published
Aug 13, 2026
Updated
Aug 13, 2026
Vendor
Gitea
Product
Gitea
Classifications
CWE-1333, CWE-407, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 13, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=1.26.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Gitea · Giteaversion=0 <=1.26.4

Published CVSS scores

7.5CISA CoordinatorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
8.7GitHubCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-1333Inefficient Regular Expression Complexity
CWE-407Inefficient Algorithmic Complexity
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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