CVE-2026-50024

GitHacker is a tool that restores Git repositories from exposed .git directories. In 1.1.7 and earlier, add_head_file_tasks parses an attacker-controlled ref path from .git/HEAD and joins unvalidated path segments onto temp_dst/.git/logs/, allowing a malicious server to make GitHacker read an arbitrary local file when a victim runs the tool against the server's URL. add_hashes_parsed then scans the file for 40-character hexadecimal substrings and requests each match through .git/objects using the first two characters and remaining characters as path components, creating an attacker-observable existence oracle and disclosing matching hexadecimal fragments. Complete file contents are not returned, and the add_folder and add_task write path in shipped version 1.1.7 does not permit an escape. This issue is fixed in repository version 1.1.9.

GitHacker is a tool that restores Git repositories from exposed .git directories. In 1.1.7 and earlier, add_head_file_tasks parses an attacker-controlled ref path from .git/HEAD and joins unvalidated path segments onto temp_dst/.git/logs/, allowing a malicious server to make GitHacker read an arbitrary local file when a victim runs the tool against the server's URL. add_hashes_parsed then scans the file for 40-character hexadecimal substrings and requests each match through .git/objects using the first two characters and remaining characters as path components, creating an attacker-observable existence oracle and disclosing matching hexadecimal fragments. Complete file contents are not returned, and the add_folder and add_task write path in shipped version 1.1.7 does not permit an escape. This issue is fixed in repository version 1.1.9.

Summary

GitHacker through 1.1.7 did not validate path segments parsed from attacker-controlled .git/HEAD before joining them onto its output directory. A malicious server could coerce GitHacker into reading arbitrary local files. Contents do not stream back wholesale, but the recovery loop turns any 40-character hex substring into an outbound HTTP GET — an existence oracle for arbitrary paths plus hex-fragment exfiltration of file contents.

Details

Vulnerability

GitHacker rebuilds a remote .git/ by fetching files into temp_dst. Two functions derived filesystem paths from server-controlled content:

• add_head_file_tasks reads the downloaded .git/HEAD, parses ref: <ref-path>, and joins the raw ref-path onto temp_dst/.git/logs/ before reading the resulting file.
• add_hashes_parsed scans any file it reads for 40-character hex substrings and emits GET .git/objects/<sha[0:2]>/<sha[2:]> for each one — onto the attacker's server and into the local output tree.

Pre-fix, add_head_file_tasks did not validate the ref segments. A malicious .git/HEAD of

ref: ../../../../../../etc/passwd

caused add_head_file_tasks to traverse out of temp_dst and read /etc/passwd. The bytes flowed into add_hashes_parsed, which emitted one outbound HTTP request per 40-char-hex match — observable on the attacker's logs.

Impact

PR #65 originally classified this as arbitrary local file read. Joint analysis during coordinated disclosure narrowed the primitive: file contents do not stream back wholesale because the only egress channel is the 40-char-hex regex. In practice an attacker can:

• Existence oracle for any path on the GitHacker host (/etc/shadow, /root/.ssh/id_rsa, /home/<user>/.git-credentials, build artifacts under /tmp/).
• Hex-fragment exfiltration when the targeted file contains 40-char hex sequences: other git repos' refs / pack filenames, password hashes, HMAC-SHA1 outputs, some session tokens.

Not exploitable without victim action: the attacker must persuade the victim to run GitHacker against a URL they control. Project guidance has always been to run GitHacker inside a disposable container.

Scoping note: no write-side primitive in 1.1.7

A working write-side primitive (attacker drops content outside temp_dst via add_folder / add_task) does not reproduce against the shipped 1.1.7 source. Empirical testing by the reporter against GitHacker-1.1.7.tar.gz (25 traversal-style payloads including ....//, %2e%2e%2f, layered foo/../../, NUL bytes, backslash variants, absolute paths) yielded 0/25 escapes. Two structural reasons:

1. add_folder anchors every derived path on self.url + '.git/', so the first path component after the url_length strip is always .git. os.path.join's absolute-path short-circuit never fires.
2. Python's str.replace("..", "") is greedy non-overlapping; ....// collapses to //, ......// to ///, etc. No literal .. survives into add_task.

5f2a8ba is still the correct fix for the read-side primitive and additionally hardens add_task as defense in depth against future regressions — for example, if a later caller removes the .git/ anchor in add_folder or wires a new server-controlled segment source into add_task.

Fix

Commit 5f2a8ba introduces _is_safe_path_segment as a single trust boundary: every segment about to be joined onto temp_dst or appended to an outgoing URL is validated against an allowlist before add_task accepts it. Empty / . / .. / separators / NUL / control characters are rejected; the brittle replace("..", "") filter is removed.

The fix also tightens adjacent surfaces preemptively:

• add_folder switches to urlparse-based scheme + netloc + path comparison.
• construct_url_from_path_components percent-encodes every segment.

PR #65's two-layer defense (allowlist regex + os.path.realpath()…

GitHacker is a tool that restores Git repositories from exposed .git directories. In 1.1.7 and earlier, add_head_file_tasks parses an attacker-controlled ref path from .git/HEAD and joins unvalidated path segments onto temp_dst/.git/logs/, allowing a malicious server to make GitHacker read an arbitrary local file when a victim runs the tool against the server's URL. add_hashes_parsed then scans the file for 40-character hexadecimal substrings and requests each match through .git/objects using the first two characters and remaining characters as path components, creating an attacker-observable existence oracle and disclosing matching hexadecimal fragments. Complete file contents are not returned, and the add_folder and add_task write path in shipped version 1.1.7 does not permit an escape. This issue is fixed in repository version 1.1.9.

GitHacker is a tool that restores Git repositories from exposed .git directories. In 1.1.7 and earlier, add_head_file_tasks parses an attacker-controlled ref path from .git/HEAD and joins unvalidated path segments onto temp_dst/.git/logs/, allowing a malicious server to make GitHacker read an arbitrary local file when a victim runs the tool against the server's URL. add_hashes_parsed then scans the file for 40-character hexadecimal substrings and requests each match through .git/objects using the first two characters and remaining characters as path components, creating an attacker-observable existence oracle and disclosing matching hexadecimal fragments. Complete file contents are not returned, and the add_folder and add_task write path in shipped version 1.1.7 does not permit an escape. This issue is fixed in repository version 1.1.9.

Summary

GitHacker through 1.1.7 did not validate path segments parsed from attacker-controlled .git/HEAD before joining them onto its output directory. A malicious server could coerce GitHacker into reading arbitrary local files. Contents do not stream back wholesale, but the recovery loop turns any 40-character hex substring into an outbound HTTP GET — an existence oracle for arbitrary paths plus hex-fragment exfiltration of file contents.

Details

Vulnerability

GitHacker rebuilds a remote .git/ by fetching files into temp_dst. Two functions derived filesystem paths from server-controlled content:

• add_head_file_tasks reads the downloaded .git/HEAD, parses ref: <ref-path>, and joins the raw ref-path onto temp_dst/.git/logs/ before reading the resulting file.
• add_hashes_parsed scans any file it reads for 40-character hex substrings and emits GET .git/objects/<sha[0:2]>/<sha[2:]> for each one — onto the attacker's server and into the local output tree.

Pre-fix, add_head_file_tasks did not validate the ref segments. A malicious .git/HEAD of

ref: ../../../../../../etc/passwd

caused add_head_file_tasks to traverse out of temp_dst and read /etc/passwd. The bytes flowed into add_hashes_parsed, which emitted one outbound HTTP request per 40-char-hex match — observable on the attacker's logs.

Impact

PR #65 originally classified this as arbitrary local file read. Joint analysis during coordinated disclosure narrowed the primitive: file contents do not stream back wholesale because the only egress channel is the 40-char-hex regex. In practice an attacker can:

• Existence oracle for any path on the GitHacker host (/etc/shadow, /root/.ssh/id_rsa, /home/<user>/.git-credentials, build artifacts under /tmp/).
• Hex-fragment exfiltration when the targeted file contains 40-char hex sequences: other git repos' refs / pack filenames, password hashes, HMAC-SHA1 outputs, some session tokens.

Not exploitable without victim action: the attacker must persuade the victim to run GitHacker against a URL they control. Project guidance has always been to run GitHacker inside a disposable container.

Scoping note: no write-side primitive in 1.1.7

A working write-side primitive (attacker drops content outside temp_dst via add_folder / add_task) does not reproduce against the shipped 1.1.7 source. Empirical testing by the reporter against GitHacker-1.1.7.tar.gz (25 traversal-style payloads including ....//, %2e%2e%2f, layered foo/../../, NUL bytes, backslash variants, absolute paths) yielded 0/25 escapes. Two structural reasons:

1. add_folder anchors every derived path on self.url + '.git/', so the first path component after the url_length strip is always .git. os.path.join's absolute-path short-circuit never fires.
2. Python's str.replace("..", "") is greedy non-overlapping; ....// collapses to //, ......// to ///, etc. No literal .. survives into add_task.

5f2a8ba is still the correct fix for the read-side primitive and additionally hardens add_task as defense in depth against future regressions — for example, if a later caller removes the .git/ anchor in add_folder or wires a new server-controlled segment source into add_task.

Fix

Commit 5f2a8ba introduces _is_safe_path_segment as a single trust boundary: every segment about to be joined onto temp_dst or appended to an outgoing URL is validated against an allowlist before add_task accepts it. Empty / . / .. / separators / NUL / control characters are rejected; the brittle replace("..", "") filter is removed.

The fix also tightens adjacent surfaces preemptively:

• add_folder switches to urlparse-based scheme + netloc + path comparison.
• construct_url_from_path_components percent-encodes every segment.

PR #65's two-layer defense (allowlist regex + os.path.realpath()…

Summary

GitHacker through 1.1.7 did not validate path segments parsed from attacker-controlled .git/HEAD before joining them onto its output directory. A malicious server could coerce GitHacker into reading arbitrary local files. Contents do not stream back wholesale, but the recovery loop turns any 40-character hex substring into an outbound HTTP GET — an existence oracle for arbitrary paths plus hex-fragment exfiltration of file contents.

Details

Vulnerability

GitHacker rebuilds a remote .git/ by fetching files into temp_dst. Two functions derived filesystem paths from server-controlled content:

• add_head_file_tasks reads the downloaded .git/HEAD, parses ref: <ref-path>, and joins the raw ref-path onto temp_dst/.git/logs/ before reading the resulting file.
• add_hashes_parsed scans any file it reads for 40-character hex substrings and emits GET .git/objects/<sha[0:2]>/<sha[2:]> for each one — onto the attacker's server and into the local output tree.

Pre-fix, add_head_file_tasks did not validate the ref segments. A malicious .git/HEAD of

ref: ../../../../../../etc/passwd

caused add_head_file_tasks to traverse out of temp_dst and read /etc/passwd. The bytes flowed into add_hashes_parsed, which emitted one outbound HTTP request per 40-char-hex match — observable on the attacker's logs.

Impact

PR #65 originally classified this as arbitrary local file read. Joint analysis during coordinated disclosure narrowed the primitive: file contents do not stream back wholesale because the only egress channel is the 40-char-hex regex. In practice an attacker can:

• Existence oracle for any path on the GitHacker host (/etc/shadow, /root/.ssh/id_rsa, /home/<user>/.git-credentials, build artifacts under /tmp/).
• Hex-fragment exfiltration when the targeted file contains 40-char hex sequences: other git repos' refs / pack filenames, password hashes, HMAC-SHA1 outputs, some session tokens.

Not exploitable without victim action: the attacker must persuade the victim to run GitHacker against a URL they control. Project guidance has always been to run GitHacker inside a disposable container.

Scoping note: no write-side primitive in 1.1.7

A working write-side primitive (attacker drops content outside temp_dst via add_folder / add_task) does not reproduce against the shipped 1.1.7 source. Empirical testing by the reporter against GitHacker-1.1.7.tar.gz (25 traversal-style payloads including ....//, %2e%2e%2f, layered foo/../../, NUL bytes, backslash variants, absolute paths) yielded 0/25 escapes. Two structural reasons:

1. add_folder anchors every derived path on self.url + '.git/', so the first path component after the url_length strip is always .git. os.path.join's absolute-path short-circuit never fires.
2. Python's str.replace("..", "") is greedy non-overlapping; ....// collapses to //, ......// to ///, etc. No literal .. survives into add_task.

5f2a8ba is still the correct fix for the read-side primitive and additionally hardens add_task as defense in depth against future regressions — for example, if a later caller removes the .git/ anchor in add_folder or wires a new server-controlled segment source into add_task.

Fix

Commit 5f2a8ba introduces _is_safe_path_segment as a single trust boundary: every segment about to be joined onto temp_dst or appended to an outgoing URL is validated against an allowlist before add_task accepts it. Empty / . / .. / separators / NUL / control characters are rejected; the brittle replace("..", "") filter is removed.

The fix also tightens adjacent surfaces preemptively:

• add_folder switches to urlparse-based scheme + netloc + path comparison.
• construct_url_from_path_components percent-encodes every segment.

PR #65's two-layer defense (allowlist regex + os.path.realpath()…