CVE-2026-3854
A public proof of concept exists; no exploitation attested.
- Published2026-03-10
- Fixed in3.19.3 · 3.18.6 · 3.17.12 · 3.16.15 · 3.15.19 · 3.14.24
- WeaknessCWE-77
Am I affected?
Debian, Ubuntu or Red Hat sometimes backport a fix without changing the upstream version number: such a version reads « to verify », never « affected ».With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.
Description
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.
Timeline
dates in UTC- 2026-03-1018:19CVE publishedNVD
- 2026-10-2319:23First public proof of conceptPoC-in-GitHub
Observed activity
isMalicious corpus · updated 2026-10-23 21:37 UTCBlock these indicators
- Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-3854?format=txt
- CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-3854?format=csv
- TAXII collection of exploited CVEs
- The EDL and CSV take an API key on the Pro plan.
Versions per branch
NVD| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 3.19 | ≥ 3.19.0, < 3.19.3 | 3.19.3 | NVD |
| 3.18 | ≥ 3.18.0, < 3.18.6 | 3.18.6 | NVD |
| 3.17 | ≥ 3.17.0, < 3.17.12 | 3.17.12 | NVD |
| 3.16 | ≥ 3.16.0, < 3.16.15 | 3.16.15 | NVD |
| 3.15 | ≥ 3.15.0, < 3.15.19 | 3.15.19 | NVD |
| 3.14 | < 3.14.24 | 3.14.24 | NVD |
as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.
Fix
- Update Github enterprise server to 3.19.3 · 3.18.6 · 3.17.12 · 3.16.15 · 3.15.19 · 3.14.24
Detection
read 2026-10-23 19:25 UTC- Nuclei template
- none so far ProjectDiscovery
- Exploit-DB
- no entry Exploit-DB
- Proof-of-concept repositories
- 7 repositories, unverified5kr1pt/CVE-2026-3854LACHHAB-Anas/Exploit_CVE-2026-3854lysophavin18/CVE-2026-3854-PoCsimondankelmann/cve-2026-3854-testisagoakira/ghes-cve-scanner PoC-in-GitHub
Sources
- CISA-ADPSSVC decisionnone2026-04-28
- OpenCVESSVC decisionnone—
- CNACVSS 4.08.7read 2026-10-23
- NVDCVSS 3.18.8read 2026-10-23
- CNAweakness (CWE)CWE-77read 2026-10-23
- FIRST EPSSEPSS score1.5 %2026-10-23
- PoC-in-GitHubproof of concept7read 2026-10-23
Technical details
- CVSS v3 Vector
- CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CVSS 4.0 vector
- 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
- Published
- 2026-03-10
- Last Modified
- 2026-06-17
- NVD status
- Modified
Frequently asked questions
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