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Stack-based Buffer OverflowWeakness · CWE-121

CVE-2026-55738

HIGH · 8.8 CVSS v3.1 Published 2026-06-17
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
95/100
Remediation priority · Urgent
Remotely reachable No privileges

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A stack-based buffer overflow exists in the raw_to_header function in src/microtar.c in rxi microtar 0.1.0. The function copies the 100-byte name and linkname fields of a TAR header with strcpy without guaranteeing null termination of the source.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A stack-based buffer overflow exists in the raw_to_header() function in rxi microtar 0.1.0. The function uses strcpy() to copy the 100-byte name and linkname fields from a TAR header without ensuring null termination. When a crafted TAR archive contains these fields with no null terminator, strcpy() reads and writes beyond the 512-byte stack buffer, causing out-of-bounds read and stack buffer overflow.

MitigationReplace strcpy() with safe string handling (e.g., strncpy with explicit null-termination or manual bounds-checked copy) for the name and linkname fields in raw_to_header() to ensure null termination and prevent overflow.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify rxi microtar library usage
    Search the codebase for 'microtar' in source files, headers, or dependency manifests (package.json, CMakeLists.txt, Makefile, vendor directories). Look for #include <microtar.h> or similar imports.
    Affected if The application or library includes and uses rxi microtar for TAR archive handling.
  2. Verify microtar version is 0.1.0
    Check the version declaration in the microtar header file (typically microtar.h) or version file. Compare against the library binary or source version identifier.
    Affected if The installed microtar version is exactly 0.1.0.
  3. Confirm raw_to_header() function is invoked
    Search the codebase for calls to mtar_read_header(), mtar_read_header_raw(), or direct calls to raw_to_header(). These functions parse TAR file entries and trigger the vulnerable code path.
    Affected if The code calls functions that invoke raw_to_header() to parse TAR file headers.
  4. Check if processing untrusted TAR files
    Review application logic to determine if it opens, reads, or extracts TAR archives from untrusted sources (user uploads, network input, external APIs).
    Affected if The application processes TAR files from untrusted or external sources without prior validation.
  5. Inspect strcpy usage in raw_to_header
    Examine the raw_to_header() function implementation in microtar source (typically microtar.c). Look for strcpy() calls copying name or linkname fields into fixed-size buffers without explicit null-termination checks.
    Affected if The raw_to_header() function uses strcpy() for name/linkname fields without bounds checking or null-termination guarantees.

The environment is affected if rxi microtar version 0.1.0 is used and the application processes untrusted TAR archives, allowing a crafted archive without null-terminated name/linkname fields to trigger the stack buffer overflow in raw_to_header().

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Replace strcpy() with safe string handling (e.g., strncpy with explicit null-termination or manual bounds-checked copy) for the name and linkname fields in raw_to_header() to ensure null termination and prevent overflow.

Recommended fix Moderate confidence
  1. 1. Download the microtar 0.1.0 source code.
  2. 2. Open src/microtar.c and locate the raw_to_header() function.
  3. 3. Add a null terminator to the name and linkname fields before they are used. For example, after the strcpy() calls, set header->name[99] = '\0' and header->linkname[99] = '\0'.
  4. 4. Alternatively, replace strcpy() with strncpy(header->name, raw+0, 99) and set header->name[99] = '\0' (same for linkname).
  5. 5. Rebuild the library (e.g., run make or the appropriate build command).
  6. 6. Replace the old library binary in your project with the newly compiled one.
  7. 7. Test the fix by parsing a crafted TAR archive and verify that the stack-buffer-overflow no longer occurs (e.g., run with AddressSanitizer).

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,390
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-55738 in production — separate from our analysis above.

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