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VulnerabilityPublished Updated

CVE-2026-56657: code.gitea.io/gitea · Gitea SSH Key Parser Denial of Service

Affects code.gitea.io/giteaSource GCVE Database

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Authoritative record:CVE-2026-56657· Medium 6.2

Not known to be exploited · CVSS 6.2 Medium : upgrade to 1.27.0 when convenient.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score
6.2Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 1.27.0
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

t = 0 is the CVE’s publication on cve.org

  1. Disclosed: evidence found.

    CVE published 13 Aug 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: evidence found.

    CISA SSVC: proof of concept public

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

Timeline

  1. CVE ID reserved

    by Gitea Limited

    , 36 days before disclosure

  2. CVE published

    on cve.org

    , t = 0

  3. CISA SSVC assessment

    proof of concept public

    , 2 hours after disclosure

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CISA SSVC, the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

Upgrade code.gitea.io/gitea and gitea.dev to 1.27.0.

Affected software

ProductAffectedFixed in
Gocode.gitea.io/giteaAffected
  • <1.27.0
Fixed in
  • 1.27.0
Gogitea.devAffected
  • <1.27.0
Fixed in
  • 1.27.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A patch is available for this vulnerability. Users should upgrade to Gitea version 1.27.0 or later to remediate the issue. Until patched, restricting access to the SSH key ingestion endpoint to trusted users and monitoring for unusual resource consumption may help mitigate risk.

Description

Gitea versions prior to 1.27.0 have a denial of service vulnerability in the SSH key ingestion endpoint. The flaw is due to an O(N²) string concatenation loop in the SSH2 key normalization function that lacks input size limits. An authenticated user can submit a maliciously large SSH2 formatted key, causing excessive CPU and memory usage that may take the server offline. This vulnerability is identified as CVE-2026-56657 and is classified as a moderate severity issue. A patch is available to address this vulnerability.

References

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