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CVE Record

CVE-2019-11921: An out of bounds write is possible via a specially crafted packet in certain configurations of Proxygen due...

An out of bounds write is possible via a specially crafted packet in certain configurations of Proxygen due to improper handling of Base64 when parsing malformed binary content in Structured HTTP Headers. This issue affects versions of proxygen prior to v2019.07.22.00.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

Proxygen had a memory-safety flaw where malformed binary content in Structured HTTP Headers could cause an out-of-bounds write. The sources say this affects Proxygen versions before v2019.07.22.00 in certain configurations. There is no CVSS score or confirmed active exploitation in the provided sources.

Executive priority

Treat this as a targeted exposure verification item, not a confirmed emergency. If Proxygen is present before v2019.07.22.00 on exposed services, prioritize upgrade because out-of-bounds writes can have serious reliability and security impact.

Technical view

CVE-2019-11921 is an out-of-bounds write in Facebook Proxygen caused by improper Base64 handling while parsing malformed binary content in Structured HTTP Headers. The vulnerable range is described as versions prior to v2019.07.22.00. Configuration-dependent reachability is noted, but the sources do not define the exact configurations.

Likely exposure

Exposure is most likely where Facebook Proxygen is deployed or embedded at versions before v2019.07.22.00 and processes Structured HTTP Headers. Internet-facing proxy or HTTP service roles should be checked first. The provided evidence does not identify downstream products or distributions.

Exploitation context

The source bundle does not show CISA KEV listing or cited evidence of active exploitation. The described trigger is a specially crafted packet reaching vulnerable parsing logic, but the exact operational preconditions are not fully documented in the provided sources.

Researcher notes

Key gaps are missing CVSS, missing CWE, and undefined “certain configurations.” Validation should focus on version provenance and parser reachability. Do not assume exploitation or affected downstream products without additional vendor-specific evidence.

Mitigation direction

  • Inventory services that deploy, embed, or vendor Facebook Proxygen.
  • Upgrade Proxygen to v2019.07.22.00 or later where vulnerable versions are present.
  • Prioritize externally reachable HTTP proxy or service components using Proxygen.
  • Review Facebook’s advisory and linked commit for vendor-confirmed remediation details.
  • If packaged through another product, request vendor guidance on Proxygen version exposure.

Validation and detection

  • Check dependency manifests, SBOMs, build logs, and container images for Proxygen versions.
  • Confirm running services use Proxygen v2019.07.22.00 or later.
  • Determine whether Structured HTTP Headers parsing is enabled and reachable.
  • Verify the remediation is present across production, staging, and disaster recovery builds.
  • Review crash and memory-safety telemetry for suspicious malformed-header parsing failures.
Prepared
Confidence
medium
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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ATT&CK lookup starting points

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CVE-2019-11921 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
3Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
FacebookProxygenv2019.07.22.00, unspecifiedListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.