CVE-2026-26247
Gitea OAuth2 PKCE S256 challenges are not enforced during token exchange
Description
Gitea versions before 1.25.5 do not persist the OAuth2 PKCE S256 challenge method correctly during authorization, allowing token exchange without the expected verifier check.
INFO
Published Date :
July 3, 2026, 9:16 p.m.
Last Modified :
July 7, 2026, 6:16 p.m.
Remotely Exploit :
Yes !
Source :
88ee5874-cf24-4952-aea0-31affedb7ff2
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | CRITICAL | 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
Solution
- Update Gitea to version 1.25.5 or later.
- Verify OAuth2 PKCE challenge method persistence.
- Review access token security configurations.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-26247.
| URL | Resource |
|---|---|
| https://blog.gitea.com/release-of-1.25.5/ | |
| https://github.com/go-gitea/gitea/pull/36462 | |
| https://github.com/go-gitea/gitea/pull/36477 | |
| https://github.com/go-gitea/gitea/releases/tag/v1.25.5 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-26247 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-26247
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-26247 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-26247 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 07, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N Added SSVC {'id': 'CVE-2026-26247', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-07-07T16:21:34.783006Z'} -
New CVE Received by 88ee5874-cf24-4952-aea0-31affedb7ff2
Jul. 03, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'Gitea', 'product': 'Gitea Open Source Git Server', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '1.25.5', 'versionType': 'semver'}], 'defaultStatus': 'unaffected'}] Added Description Gitea versions before 1.25.5 do not persist the OAuth2 PKCE S256 challenge method correctly during authorization, allowing token exchange without the expected verifier check. Added CWE CWE-284 Added Reference https://blog.gitea.com/release-of-1.25.5/ Added Reference https://github.com/go-gitea/gitea/pull/36462 Added Reference https://github.com/go-gitea/gitea/pull/36477 Added Reference https://github.com/go-gitea/gitea/releases/tag/v1.25.5