8.8

CVE-2026-4296: github enterprise_server Incorrect Regular Expression

CVSS: 8.8v3.1HighAnalyzed
Published 21-04-2026Last modified 22-04-2026
Open JSON

Vulnerability summary

CVE-2026-4296 is a high (CVSS 8.8) Incorrect Regular Expression vulnerability in github enterprise_server. EPSS estimates a 0.74% chance of exploitation in the next 30 days, higher than 53.7% of scored vulnerabilities.

Overall risk
35/100
0100
Medium · default modelHow is this calculated?
CVSS score
8.8/10
010
High · v3.1 (NVD)
EPSS score
0.74%
0%100%
Low · +0.31 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 21-04-2026
    PublishedVulnerability first disclosed.
  2. 22-04-2026
    Last modifiedVulnerability information updated.

Description

An incorrect regular expression vulnerability was identified in GitHub Enterprise Server that allowed an attacker to bypass OAuth redirect URI validation. An attacker with knowledge of a first-party OAuth application's registered callback URL could craft a malicious authorization link that, when clicked by a victim, would redirect the OAuth authorization code to an attacker-controlled domain. This could allow the attacker to gain unauthorized access to the victim's account with the scopes granted to the OAuth application. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21 and was fixed in versions 3.20.1, 3.19.5, 3.18.8, 3.17.14, 3.16.17, 3.15.21, 3.14.26. This vulnerability was reported via the GitHub Bug Bounty program.

CVSS metrics

3 scores · 2 sources · 2 versions

EPSS trend

Probability

0.74%

Chance of exploitation in the next 30 days

Percentile

54%

Versus all other CVEs

30-day change

+0.31 pp

From 0.43% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.74%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Github1 product
  • enterprise_server≥ 3.14.0, ≤ 3.14.25 | ≥ 3.15.0, ≤ 3.15.20 | ≥ 3.16.0, ≤ 3.16.16 | ≥ 3.17.0, ≤ 3.17.13 | ≥ 3.18.0, ≤ 3.18.7 | ≥ 3.19.0, ≤ 3.19.4 | ≥ 3.20.0, < 3.20.1 | < 3.14.26 | ≥ 3.15.0, < 3.15.21 | ≥ 3.16.0, < 3.16.17 | ≥ 3.17.0, < 3.17.14 | ≥ 3.18.0, < 3.18.8 | ≥ 3.19.0, < 3.19.5 | 3.20.0

1 vendor · 1 product

References

7 links