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CVE-2026-3854

HIGHCVSS 8.7/10EPSS 24.46%

Last modified

CVE-2026-3854 is a high-severity vulnerability rated 8.7/10 on the CVSS scale. 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. EPSS estimates a 24.46% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
8.8/10

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

CVSS 4.0
8.7/10

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 Probability
24.46%

97.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
GithubEnterprise Server< 3.14.24
GithubEnterprise Server>= 3.15.0, < 3.15.19
GithubEnterprise Server>= 3.16.0, < 3.16.15
GithubEnterprise Server>= 3.17.0, < 3.17.12
GithubEnterprise Server>= 3.18.0, < 3.18.6
GithubEnterprise Server>= 3.19.0, < 3.19.3

References

Timeline

Published
Last Modified
Status
Modified

Frequently Asked Questions

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.
How severe is CVE-2026-3854?
CVE-2026-3854 has a CVSS score of 8.7/10 (HIGH severity). The EPSS model estimates a 24.46% probability of exploitation in the next 30 days.
How do I fix CVE-2026-3854?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-3854?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST