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Double FreeWeakness · CWE-415

CVE-2020-37239

CRITICAL · 9.8 CVSS v3.1 Published 2026-05-16
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Public exploit Remotely reachable No privileges Zero-click

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
libbabl 0.1.62 contains a broken double free detection vulnerability that allows attackers to bypass memory safety checks by exploiting signature overwriting in freed chunks. Attackers can call babl_free() twice on the same pointer without triggering detection, as libc's malloc metadata overwrites babl's signature field upon freeing, enabling potential memory corruption and code execution.

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

libbabl 0.1.62 contains a broken double free detection vulnerability in babl_free() where the library's signature-based detection can be bypassed because libc's malloc metadata overwrites babl's signature field upon freeing. This allows attackers to call babl_free() twice on the same pointer without triggering detection, leading to potential memory corruption and code execution.

MitigationUpgrade to a patched version of libbabl (if available) that implements proper double-free detection using a robust mechanism not susceptible to malloc metadata overwriting, or implement application-level mitigations such as nullifying pointers immediately after freeing and using memory sanitizers during development.

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
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/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. Locate libbabl installation
    Search for the libbabl shared library file (typically named libbabl.so, libbabl-0.1.so, or similar) in common library directories such as /usr/lib, /usr/local/lib, or within application bundles. Use command: find /usr -name 'libbabl*' 2>/dev/null
    Affected if libbabl library file is found on the system
  2. Determine installed libbabl version
    Run pkg-config --modversion libbabl-0.1 or check the library filename which often includes the version (e.g., libbabl-0.1-62.so). Alternatively, use ldd on applications linked against babl or check package manager listings (dpkg -l | grep babl, rpm -qa | grep babl)
    Affected if Installed version is 0.1.62 exactly, or falls within the vulnerable range before proper fix was implemented
  3. Identify applications using babl_free()
    Search application source code or binaries for calls to babl_free() function. Use grep -r 'babl_free' on source trees or check dynamic symbols with nm/objdump on compiled binaries linked against libbabl
    Affected if Codebase contains direct calls to babl_free() function, making it subject to the double-free vulnerability
  4. Check for double-free or memory corruption symptoms
    Run affected applications under memory debugging tools such as valgrind --track-origins=yes or AddressSanitizer (ASAN) to detect heap corruption, double-free errors, or use-after-free conditions when babl_free() is invoked
    Affected if Memory sanitizer reports double-free or heap corruption related to babl_free() calls

The environment is affected if libbabl version 0.1.62 is installed AND applications actively use the babl_free() function to free memory allocations.

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

Upgrade to a patched version of libbabl (if available) that implements proper double-free detection using a robust mechanism not susceptible to malloc metadata overwriting, or implement application-level mitigations such as nullifying pointers immediately after freeing and using memory sanitizers during development.

Recommended fix Moderate confidence

libbabl 0.1.66 or later stable release

  1. 1. Identify all applications and build systems that link against libbabl version 0.1.62 in your environment
  2. 2. Obtain a newer version of libbabl from the official source (www.gegl.org) or your distribution's package repository
  3. 3. Ensure you obtain libbabl version 0.1.66 or later, which contains the fix for the broken double free detection
  4. 4. Rebuild or update all dependent applications (such as GIMP) against the new libbabl library
  5. 5. Verify the upgrade by checking the library version with: pkg-config --modversion babl or dpkg -l | grep babl
  6. 6. Test that applications using babl (e.g., GIMP) function correctly with the updated library
Caveat Likely minimal; as a patch release for a bug fix, backward API compatibility should be preserved. Test critical workflows in dependent applications like GIMP.

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

Have this fixed Scoped from the published advisory
  • Consultation4.0 h
  • Implementation12.0 h
  • Testing8.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,880
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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-2020-37239 in production — separate from our analysis above.

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What belongs here
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