CVE.org (no NVD analysis yet)· CNA Gitea

CVE-2026-109553: Gitea SSH certificate principal impersonation of other users

Noroxi assessment

Priority: Monitor (action score 30/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.17% (FIRST EPSS).
Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. Special conditions such as timing or configuration are required.
No fixed version is recorded, but the references include a patch (commit or PR) link.

Low priority for now. See the fix and affected versions sections below.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

Gitea resolved the principals of an SSH certificate by searching the content of all stored public keys instead of only principal keys. When Gitea trusts a user certificate authority (`SSH_TRUSTED_USER_CA_KEYS`) and accepts arbitrary principals (`SSH_AUTHORIZED_PRINCIPALS_ALLOW=anything`), a user could register another user's public key line as their own principal, or a holder of a certificate signed by that authority could list it, and then authenticate as the owner of that key through the HTTP signature API and the built-in SSH server. Instances that do not trust a user certificate authority are not affected.

HighCVSS 7.5 · v3.1—No exploit No fix recorded

Auth bypass

Published: Oct 18, 2026
Updated: Nov 2, 2026
EPSS: 0.1% · 7th percentile
CWE: CWE-287

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 30 / 40 · 7.5 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.1%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: total

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
No fixed version yet

If any of these changes, we'll tell you in the daily email digest.

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Gitea). Independent of NVD's CPE analysis and usually ahead of it.

Gitea Gitea
- up to and including 28.1.0affected · semver

Same product

gitea: all records

Other highest-scoring records for the same primary product.

CVE-2026-60004Gitea before 1.27.1 allows remote code execution via the diffpatch API through Git hook installation.KEV
76This week
CVE-2026-59774Gitea Org-mode file disclosure and code execution
60This week
CVE-2022-30781Gitea before 1.16.7 does not escape git fetch remote.
60This week

Published before and after this one in the same product

← EarlierCVE-2026-107618Oct 18, 2026 · Gitea cross-site request forgery on repository topics
32Monitor
← EarlierCVE-2026-107686Oct 18, 2026 · Gitea reactions accepted on locked issues and comments
17Monitor
Later →CVE-2026-109844Oct 18, 2026 · Gitea watched repositories API disclosure after access revocation
17Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

https://github.com/DshtAngerreporter
https://github.com/silverwindremediation developer
https://github.com/wxiaoguangremediation developer
https://github.com/bircniremediation developer

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

CVE-2026-7327812 days apartGitea WebAuthn bypass during OAuth and OIDC sign-in
39Monitor
CVE-2026-12026314 days apartGitea OAuth2 account auto-linking takeover through the sign-up form
39Monitor
CVE-2026-10102312 days apartGitea OAuth2 refresh token grant accepts access tokens
36Monitor
CVE-2026-9640412 days apartGitea installer authentication bypass for existing accounts
32Monitor
CVE-2026-1046270 days apartGitea OpenID account linking without session binding
21Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

CVE-2026-738004 days apartGitea reusable workflow secret exposure in pull_request_target
35Monitor
CVE-2026-10102712 days apartGitea migration SSRF through ALLOWED_DOMAINS address check bypass
30Monitor
CVE-2026-10102912 days apartGitea migration and pull mirror SSRF through multi-answer DNS
17Monitor
CVE-2026-9640012 days apartGitea migration SSRF to reserved addresses through ALLOWED_DOMAINS
17Monitor

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
A low-privileged account is enough.
No user action is required.
Special conditions such as timing or configuration are required.

If successful

Confidentiality: high · data can be read
Integrity: high · data or configuration can be modified
Availability: high · the service can be disrupted

Attack vector: Network
Attack complexity: High
Privileges required: Low
User interaction: None
Scope: Unchanged
Confidentiality impact: High
Integrity impact: High
Availability impact: High

Weakness class (CWE)

CWE-287 · Improper Authentication

CVSS vector

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

nvd-secondary

Root cause

Authentication is added route by route instead of being enforced in one place. When a route added later bypasses the shared middleware, the session check never runs for it.

The bug in code

The whole CWE-287 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1app.use("/admin", requireSession, adminRouter);
2

3// Route added later skips the middleware
4app.post("/admin-api/config", updateConfig);

Fixed

1const admin = express.Router();
2admin.use(requireSession, requireRole("admin"));
3

4admin.post("/config", updateConfig);
5app.use("/admin", admin);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

Change log

CVSS— → 7.5Oct 19, 2026, 10:07 PM UTC
Severity— → highOct 19, 2026, 10:07 PM UTC
SSVC exploitation— → noneOct 19, 2026, 10:07 PM UTC
Exploit maturity— → noneOct 18, 2026, 8:07 PM UTC

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References

blog.gitea.com/release-of-28.2.0/

Show all references (4 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records