CVE-2026-56657Public exploitNetwork attack vector

Service interruption via quadratic SSH2 key parsing

Published Aug 13, 2026 · Updated Aug 13, 2026

Resource exhaustion in the Gitea SSH key parser through 1.26.4 allows remote authenticated users to interrupt service via an SSH2 key. parseKeyString splits RFC 4716 input into lines and repeatedly appends body lines to an immutable string without a size bound, causing quadratic copying and allocation. An ordinary account with SSH-key management enabled can reach the API or web ingestion path; CPU and memory exhaustion can take the instance offline.

CVSS severity6.5
Medium
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in the Gitea SSH key parser through 1.26.4 allows remote authenticated users to interrupt service via an SSH2 key. parseKeyString splits RFC 4716 input into lines and repeatedly appends body lines to an immutable string without a size bound, causing quadratic copying and allocation. An ordinary account with SSH-key management enabled can reach the API or web ingestion path; CPU and memory exhaustion can take the instance offline.

The record

CVE
CVE-2026-56657
Published
Aug 13, 2026
Updated
Aug 13, 2026
Vendor
Gitea
Product
Gitea
Classifications
CWE-770, CWE-284, T1499.003
Attack vector
network
Privileges
authenticated

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 privilegesauthenticated

What is affected?

Gitea · Giteaversion=0 <=1.26.4

Published CVSS scores

6.5Red HatCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
6.2CISA ADPCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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.

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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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
CWE-284Improper Access Control
T1499.003Application Exhaustion Flood

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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