VulnerabilityPublished 10 Jul 2026

CVE-2026-54071: Arbitrary Code Execution via CMap Pickle Deserialization in babeldoc/pdfminer/cmapdb.py

Affects BabelDOCSource GCVE Database

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Authoritative record:CVE-2026-54071· High 7.8

Not known to be exploited · CVSS 7.8 High : upgrade to 0.6.3 soon.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 3.1 base score

7.8High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 31% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 0.6.3

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

Attack Vector: Local
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 21 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade BabelDOC to 0.6.3.

Affected software

Product	Affected	Fixed in
PyPIBabelDOC	Affected <0.6.3	Fixed in 0.6.3

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Description

## Arbitrary Code Execution via CMap Pickle Deserialization in babeldoc/pdfminer/cmapdb.py ### Summary BabelDOC's vendored PDF parser (`babeldoc/pdfminer/cmapdb.py`) deserializes untrusted pickle data when loading CMap files. The `_load_data()` method strips only NUL bytes from a PDF-controlled CMap name, then passes it directly to `os.path.join()` and `pickle.loads()`. Because Python's `os.path.join()` discards all preceding path components when it encounters an absolute path segment, an attacker who embeds a hex-encoded absolute path in a crafted PDF's `/Encoding` name (e.g., `/#2Ftmp#2Fattacker#2Fevil`) can redirect deserialization to any attacker-writable `.pickle.gz` file on the local system. Processing such a PDF results in arbitrary Python code execution with the privileges of the BabelDOC process. ### Details The vulnerable function is `CMapDB._load_data()` at `babeldoc/pdfminer/cmapdb.py:232–245`: ```python @classmethod def _load_data(cls, name: str) -> Any: name = name.replace("\0", "") # line 233 — only NUL is stripped filename = "%s.pickle.gz" % name # line 234 — attacker-controlled string ... for directory in cmap_paths: path = os.path.join(directory, filename) # line 241 — no realpath/canonical check if os.path.exists(path): gzfile = gzip.open(path) try: return type(str(name), (), pickle.loads(gzfile.read())) # line 245 — unconditional pickle ``` **Path injection via PDF name hex-encoding.** The PDF specification allows name objects to encode arbitrary bytes as `#xx`. The pdfminer literal-name parser (`psparser._parse_literal_hex`) decodes these sequences before handing the string to higher layers. Consequently, the PDF literal `/#2Ftmp#2Fattacker#2Fevil` is decoded to the Python string `/tmp/attacker/evil`. **Python `os.path.join()` absolute-path override.** When the decoded name starts with `/` (i.e., it is an absolute path), Python's `os.path.join(directory, name + ".pickle.gz")` ignores `directory` entirely and returns the absolute path unchanged. The trusted `cmap_paths` directories (`/usr/share/pdfminer/`, the package's own `cmap/` folder) are therefore completely bypassed. **Data flow from PDF to sink:** 1. `babeldoc/main.py:611–622` — CLI accepts a PDF path; only existence and `.pdf` suffix are checked. 2. `babeldoc/main.py:678–679` — path stored in `TranslationConfig(input_file=file)`. 3. `babeldoc/format/pdf/high_level.py:472–488` — `translation_config.input_file` enters the translate pipeline. 4. `babeldoc/format/pdf/high_level.py:805–848` — PDF saved to `temp_pdf_path` and parsed with `parse_prepared_pdf_with_new_parser_to_legacy_ir`. 5. `babeldoc/format/pdf/new_parser/native_parse.py:60–70` — prepared pages loaded and interpreted. 6. `babeldoc/format/pdf/new_parser/pymupdf_prepared_page_access.py:25–34` — PyMuPDF opens the PDF and builds page resources. 7. `babeldoc/format/pdf/new_parser/prepared_resource_builder.py:84–94` — font resources converted to `PreparedFontSpec`. 8. `babeldoc/format/pdf/new_parser/active_font_resource_runtime.py:21–35` — page resource bundle resolves root font map. 9. `babeldoc/format/pdf/new_parser/active_font_runtime.py:79–87` — each font spec projected and passed to `font_factory.create_font`. 10. `babeldoc/format/pdf/new_parser/active_direct_font_backend.py:291–292, 491–493` — CID fonts call `build_cid_cmap(spec, literal_name=literal_name)`. 11. `babeldoc/format/pdf/new_parser/runtime/cid_cmap_runtime.py:52–77` — PDF-controlled `/Encoding`/`CMapName` normalized and passed to `CMapDB.get_cmap`. `_normalize_cmap_name()` removes only a single leading `/`; all other path characters pass through. 12. `babeldoc/pdfminer/cmapdb.py:233–245` — **sink**: NUL-stripped name used verbatim to construct the path; file opened with gzip and deserialized with `pickle.loads()`. **Sanitization gaps:** - `name.replace("\0", "")` removes only the NUL byte; `..`, `/`, `\`, and hex-decoded path separators are unaffected. - There is no `os.path.realpath()`, `os.path.abspath()`, or `os.path.commonpath()` containment check before the file is opened. - There is no allowlist of known CMap names nor any integrity verification of the pickle data. **Recommended patch** (`babeldoc/pdfminer/cmapdb.py`): ```diff --- a/babeldoc/pdfminer/cmapdb.py +++ b/babeldoc/pdfminer/cmapdb.py @@ cmap_paths = ( os.environ.get("CMAP_PATH", "/usr/share/pdfminer/"), os.path.join(os.path.dirname(__file__), "cmap"), ) for directory in cmap_paths: - path = os.path.join(directory, filename) + base_dir = os.path.realpath(directory) + path = os.path.realpath(os.path.join(base_dir, filename)) + try: + if os.path.commonpath([base_dir, path]) != base_dir: + continue + except ValueError: + continue if os.path.exists(path): gzfil

CWE-502Deserialization of Untrusted Data (opens in a new tab)
Base weaknessLikelihood of exploit: MediumCWE Top 25 (2025): #15OWASP Top 10 A08:2025: Software or Data Integrity Failures (opens in a new tab)
The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.
Architecture and Design · Implementation
If available, use the signing/sealing features of the programming language to assure that deserialized data has not been tainted. For example, a hash-based message authentication code (HMAC) could be used to ensure that data has not been modified.
Implementation
When deserializing data, populate a new object rather than just deserializing. The result is that the data flows through safe input validation and that the functions are safe.
Implementation
Explicitly define a final object() to prevent deserialization.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
Deserialization (opens in a new tab)
XML Security (opens in a new tab)
XML External Entity Prevention (opens in a new tab)
Software Supply Chain Security (opens in a new tab)
OWASP ASVS 4.0.3
V1.5.2 (opens in a new tab)
V5.5.3 (opens in a new tab)
V5.5.1 (opens in a new tab)
Attack patterns
Object Injection (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

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Affected software

Description

WeaknessesCWE-502

Technical details

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