CVE-2026-71442

Executive Summary

CVE-2026-71442 is an Integer Underflow (Wrap or Wraparound) vulnerability affecting Adobe's Content Authenticity Initiative (CAI) Content Credentials component (C2Pa). A remote, unauthenticated attacker can trigger the flaw to crash the application, resulting in a persistent denial-of-service (DoS) condition. The vulnerability carries a CVSS score of 7.5 (High) and the attack does not require user interaction, making automated exploitation viable. While the EPSS score (0.00508) indicates low current exploitation likelihood, the public availability of PoC material raises the risk profile for organizations that process or validate Content Credentials metadata.

Technical Analysis

The vulnerability is classified under CWE-191 (Integer Underflow / Wrap or Wraparound). Content Credentials, part of Adobe's CAI (Content Authenticity Initiative), is a system designed to attach tamper-evident provenance metadata (signatures, edits, and provenance history) to digital media. The C2Pa component (likely the C2PA (Coalition for Content Provenance and Authenticity) reference implementation) parses these credential manifests and assertions that accompany images, video, and other assets.

The vulnerability mechanism stems from an arithmetic operation on an unsigned integer that is derived from attacker-controlled data during parsing. When a size field or length field in the Content Credentials blob is set to a value that causes an unsigned subtraction to underflow zero, the variable wraps to a large value (near 2^32 - 1 or 2^64 - 1). Subsequent memory allocation or buffer traversal operations based on this corrupted length result in either:

1. A large allocation request that fails and triggers an unhandled exception, or
2. A buffer over-read that crashes the parsing process.

Because the flaw is in the parsing logic of a network-facing or file-processing surface, the remote attack vector (AV:N) with no privileges (PR:N) and no user interaction (UI:N) is enabled. The availability impact is High (A:H) — the application terminates — while confidentiality (C:N) and integrity (I:N) are not affected; the attacker cannot exfiltrate data or modify state, only disrupt service.

Sufficient technical detail about the triggering function names or specific parser routines is not available from the NVD description; the analysis above describes the vulnerability class mechanics generically.

Exploitation Scenarios

Step 1 — Reconnaissance / Target Identification: The target is any application, service, or pipeline that ingests and parses Content Credentials manifests. This includes image galleries that display provenance data, digital asset management systems, forensic tools, and cloud-based verification APIs. An attacker identifies such a target via Shodan queries (searching for exposed CAI-related web panels or APIs) or by probing media upload endpoints.

Step 2 — Triggering the Flaw: The attacker crafts a media file (JPEG, PNG, or video) that embeds a Content Credentials block. Within the manifest container, the attacker supplies a malformed length field — for example, a length value of 0x00000000 combined with an operation that subtracts 1, or a length stored in one-byte form but interpreted as a multi-byte integer. When the parser subtracts a header size or constant (e.g., length - 0x10) from a small value, the result underflows and wraps to a very large number.

Step 3 — Payload Execution: No shellcode or code injection is required. The underflowed length value is used directly in a subsequent memory operation. The server-side parser attempts to read or allocate 0xFFFFFFFF (or similar) bytes. The allocation fails (out-of-memory) or the read causes a segmentation fault inside the parsing library. The application process crashes, logging an unhandled exception. Because this is a crash-only bug (not RCE), the "payload" is the malformed file itself, delivered via a file upload endpoint, a URL fetch (for remote manifest retrieval), or an email attachment processed by a server-side email scanner.

Step 4 — Post-Exploitation Impact: The immediate impact is a crash of the parsing service. If the service runs as part of a larger pipeline (e.g., a batch processing queue), the worker thread dies. In a containerized environment, repeated automated restarts (CrashLoopBackOff) may occur, amplifying the DoS. An attacker can resubmit the crafted file to maintain continuous downtime. If the parser runs on a shared host with inadequate isolation, resource exhaustion (allocator churn) may impact co-tenant services. There is no privilege escalation; the denial-of-service aspect is the sole end goal.

Note: No public PoC code is confirmed, but PoC status is listed as "Public." The attack chain is inferred from the vulnerability class; no specific file offsets or parser function names are available.

Impact Assessment

Business Impact: Organizations that heavily rely on CAI/C2PA-enabled workflows — such as news agencies, creative studios, and digital forensics firms — face service disruption if their ingestion or verification pipelines crash. If the parsing is part of a high-availability API endpoint, an attacker can force a tire-kick scenario where the service must be manually restarted, breaking SLAs.

Affected Systems: All applications bundling the affected Adobe CAI/C2Pa library version. Since the affected version range is not publicly listed, the blast radius is potentially enormous, covering every deployment of the vulnerable library — from mobile apps (iOS/Android) to server-side content moderation systems and desktop post-production tools.

CVSS Subscores: Availability (A:H) is the sole impact; attacking complexity is Low, the attack vector is Network, and no privileges or user interaction are required. This scores 7.5 (High). The lack of confidentiality/integrity impact limits the score from being Critical.

Blast Radius: The attack is remotely reachable but constrained to a crash. While the system is down, data processing halts; however, an attacker cannot steal, modify, or encrypt data. The persistence of the DoS depends on the application's restart mechanism — auto-restarting services may be repeatedly crashed with a single file at each startup.

Detection Guidance

Sigma Rule

title: Potential CVE-2026-71442 Content Credentials Parser Crash
id: 6a8f4c21-8b4e-4c9a-b2f5-7c1d6a3e9f01
status: experimental
description: Detects crash indicators from a C2PA/Content Credentials parsing library (integer underflow).
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2026-71442
author: Valtersit Threat Intel
logsource:
    category: application
    product: c2pa
detection:
    selection_crash:
        event.type: "error"
        message|contains:
            - "integer underflow"
            - "out of memory"
            - "allocation size too big"
            - "segmentation fault"
            - "core dumped"
            - "c2pa::parser"
            - "ca_interop"
    selection_panic:
        process.exit_code:
            - -11  # SIGSEGV
            - 134   # SIGABRT
            - 137   # SIGKILL (OOM killed)
    condition: selection_crash OR selection_panic
    timeframe: 5m
level: medium
falsepositives:
    - Legitimate malformed files from deprecated SDK versions
    - Resource exhaustion from unrelated large media files
tags:
    - attack.t1499
    - cve.2026.71442

YARA Rule

rule CVE_2026_71442_ContentCredentials_Underflow {
    meta:
        author = "Valtersit Threat Intel"
        description = "Detects crafted C2PA/Content Credentials files likely triggering integer underflow in Adobe CAI library"
        cve = "CVE-2026-71442"
        date = "2026-01-01"
        severity = "medium"
    strings:
        $c2pa_magic_jumbf = { 4A 55 4D 42 46 }          // "JUMBF"
        $c2pa_claim_v2 = "c2pa.claim" ascii
        $c2pa_assertion = "c2pa.assertions" ascii
        $jumbf_box_len = { 00 00 00 01 }                // small size header w/ box length 1 (suspicious)
        $manifest_marker = "dc:format" ascii
        $zero_len = { 00 00 00 00 00 00 00 00 }         // 8-byte zero length field
    condition:
        uint16(0) == 0xFFD8 or uint32(0) == 0x89504E47 or uint16(0) == 0x0001  // JPEG/PNG/MP4 style
        and 1 of ($c2pa_*) and (1 of ($jumbox_len*, $zero_len) or 1 of ($c2pa_*))
}

Suricata IDS Rule

alert http any any -> $HOME_NET any (msg:"CVE-2026-71442 Potential C2PA Content Credentials Parser Crash"; flow:established,to_server; content:"Content-Type"; http_header; content:"multipart/form-data"; http_header; content:"name=\"file\""; http_header; content:"JUMBF"; within:512; sid:2026071442; rev:1; classtype:attempted-dos; reference:cve,2026-71442;)

Elastic Detection

// Look for crash patterns in C2PA/CAI parser process logs
sequence by process.entity_id
    with maxspan=1m
    [ event.kind:"event" and process.name:"*c2pa*" ]
    [ event.action:"exit" and process.exit_code in (-11, 134, 137) ]
    [ any where message:*"out of memory"* or message:*"allocation size"* or message:*"integer underflow"* ]

Splunk SPL Query

index=main sourcetype=application_log
  (process=*c2pa* OR component=c2pa OR component=ca_interop)
  AND (message="*segmentation fault*" OR message="*out of memory*" OR message="*integer underflow*" OR exit_code=-11 OR exit_code=134)
  | stats count by host, source, process_name, message
  | eval severity=case(count>=5, "HIGH", count>=2, "MEDIUM", true(), "INFO")
  | sort - count

Wazuh OSSEC Rule

<group name="c2pa,">
  <rule id="120442" level="10">
    <decoded_as>json</decoded_as>
    <field name="component">c2pa</field>
    <match>integer underflow|out of memory|allocation size too big|segmentation fault</match>
    <description>C2PA/CAI parser crash detected — potential CVE-2026-71442 exploitation.</description>
    <group>dos,cve-2026-71442,attack.t1499</group>
    <mitre>
      <id>T1499</id>
    </mitre>
  </rule>
</group>

Mitigation & Patch Guidance

1) Immediate Mitigations (until a confirmed patch is applied):

• Disable or gate C2PA parsing: If the vulnerable CAI/C2Pa component is embedded in an ingestion pipeline but not business-critical, disable it. If possible, route Content Credentials parsing to a dedicated, isolated microservice that can be restarted independently.
• Input validation/rejection: If feasible without a patch, reject files containing Content Credentials manifests with anomalous size fields (e.g., length values < 0x20 when claiming a large payload). Note: this may break legitimate provenance data; perform in a staging environment first.
• Set resource limits: Enforce strict memory limits (ulimit/cgroup) on the parsing process to prevent OOM-kill cascades and restrict the blast radius of a crash.
• Rate limiting: Apply rate limiting on file upload endpoints to mitigate automated replay of the crash file.

2) Patch/Upgrade Steps:

• Patch confidence is 2/4 (CLAIMED) — a single source (NVD) claims a patch exists, but the specific version or build number has not been independently confirmed by Valtersit. Consult the official Adobe Security Bulletin for the advisory tracking ID related to CVE-2026-71442.
• Action: Check the Adobe CAI/C2Pa library version currently deployed. Wait for the vendor's official advisory to list the patched version numbers. Until the claim is independently confirmed, treat the environment as still vulnerable.
• After the patch is confirmed, upgrade the CAI/C2Pa library on all affected servers, client applications, and mobile SDKs.

3) Long-Term Hardening:

• Supply chain control: Vend all internal builds of libraries that include C2Pa. Maintain a Software Bill of Materials (SBOM) so that CVE impact assessment is real-time.
• Fuzz testing: Integrate a fuzzer (e.g., AFL++ or LibFuzzer) into the CI/CD pipeline targeting the C2PA manifest parser with malformed JUMBF and assertion structures to uncover sibling integer issues before attackers do.
• Harden the parsing environment: Run C2PA parsing in a memory-safe sandbox (e.g., WASM or gVisor) to contain crash impact.
• Monitoring: Deploy the Sigma/Elastic/Suricata detections listed above in production to alert on repeated crash attempts. Track "killer file" hashes across the fleet to block known malicious samples.

References

1. NVD Entry: https://nvd.nist.gov/vuln/detail/CVE-2026-71442 — Official CVE description and CVSS.
2. CWE-191: https://cwe.mitre.org/data/definitions/191.html — Integer Underflow (Wrap or Wraparound) class reference.
3. MITRE ATT&CK T1499: https://attack.mitre.org/techniques/T1499/ — Endpoint Denial of Service tactic mapping.
4. Adobe Security Bulletins (to be updated): https://helpx.adobe.com/security.html — Vendor advisory platform for the claimed patch (as of writing, bulletin not independently confirmed).
5. C2PA Specification: https://c2pa.org/specifications/specifications/1.4/specs/C2PA_Specification.html — Reference for the manifest parsing structure relevant to the attack surface.

Threat Actor Campaign Notes: As of the writing of this report, there are no known threat actor campaigns directly attributed to CVE-2026-71442. The EPSS score suggests a low (but non-zero) probability of exploitation in the wild. CISA KEV does not list this CVE. The PoC status is "Public," meaning that even though no dedicated Nuclei template or weaponized exploit code has been published, security researchers may repurpose publicly disclosed PoC logic. Monitor vendor advisories for any exploitation-in-the-wild announcements.