What is CVE-2026-3854?
An improper neutralization of special elements vulnerability was identified in GitHub Enterprise Server that allowed an attacker with push access to a repository to achieve remote code execution on the instance. During a git push operation, user-supplied push option values were not properly sanitized before being included in internal service headers. Because the internal header format used a delimiter character that could also appear in user input, an attacker could inject additional metadata fields through crafted push option values. This vulnerability was reported via the GitHub Bug Bounty program and has been fixed in GitHub Enterprise Server versions 3.14.25, 3.15.20, 3.16.16, 3.17.13, 3.18.7 and 3.19.4.
The record classifies CVE-2026-3854 under weakness class CWE-77. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs low-privilege credentials, needs no user interaction, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 231 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 8.8 — HIGH
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - CVSS v4.0 base score
- 8.7
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS (FIRST)
- 1.5% probability of exploitation in the next 30 days, higher than 73.5% of all scored CVEs
- CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 9.3/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2026-03-10, last modified 2026-04-29
Is CVE-2026-3854 being exploited?
Weaponised exploit code for CVE-2026-3854 is publicly available. 8 public proof-of-concept repositories are tracked for this identifier.
- royaleybovich/CVE-2026-3854-lab (github)
- lysophavin18/CVE-2026-3854-PoC (github)
- 5kr1pt/CVE-2026-3854 (github)
- LACHHAB-Anas/Exploit_CVE-2026-3854 (github)
- simondankelmann/cve-2026-3854-test (github)
- isagoakira/ghes-cve-scanner (github)
- ridhinva/ghe-push-option-rce-scanner (github)
- trickest/cve (trickest)
Affected products and versions
- Github: Enterprise Server
How to fix CVE-2026-3854
The record marks a vendor fix as available for CVE-2026-3854. Vendor advisory: https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.4. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.
Threat activity tracking CVE-2026-3854
2 tracked threats in the Threadlinqs corpus reference CVE-2026-3854, either in the campaign’s CVE list or as an indicator on the campaign record.
Sources
Enriched from CVE.org, FIRST EPSS, GitHub Security Advisories, public proof-of-concept repositories. Last verified by Threadlinqs on .
Other references
- docs.github.com
- docs.github.com (release notes)
- docs.github.com (release notes)
- docs.github.com (release notes)
- docs.github.com (release notes)
Showing 5 of 7 recorded references.