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go-git missing validation decoding Index v4 files leads to panic

Low severity GitHub Reviewed Published Mar 29, 2026 in go-git/go-git • Updated Mar 31, 2026

Package

gomod github.com/go-git/go-git/v5 (Go)

Affected versions

<= 5.17.0

Patched versions

5.17.1

Description

Impact

go-git’s index decoder for format version 4 fails to validate the path name prefix length before applying it to the previously decoded path name. A maliciously crafted index file can trigger an out-of-bounds slice operation, resulting in a runtime panic during normal index parsing.

This issue only affects Git index format version 4. Earlier formats (go-git supports only v2 and v3) are not vulnerable to this issue.

An attacker able to supply a crafted .git/index file can cause applications using go-git to panic while reading the index. If the application does not recover from panics, this results in process termination, leading to a denial-of-service (DoS) condition.

Exploitation requires the ability to modify or inject a Git index file within the local repository in disk. This typically implies write access to the .git directory.

Patches

Users should upgrade to v5.17.1, or the latest v6 pseudo-version, in order to mitigate this vulnerability.

Credit

go-git maintainers thank @kq5y for finding and reporting this issue privately to the go-git project.

References

@pjbgf pjbgf published to go-git/go-git Mar 29, 2026
Published to the GitHub Advisory Database Mar 30, 2026
Reviewed Mar 30, 2026
Published by the National Vulnerability Database Mar 31, 2026
Last updated Mar 31, 2026

Severity

Low

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:L

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(2nd percentile)

Weaknesses

Improper Validation of Array Index

The product uses untrusted input when calculating or using an array index, but the product does not validate or incorrectly validates the index to ensure the index references a valid position within the array. Learn more on MITRE.

CVE ID

CVE-2026-33762

GHSA ID

GHSA-gm2x-2g9h-ccm8

Source code

Credits

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