Skip to main content
cve.nowby Sazabi
Menu
CVEs

CVE

When a remote, unauthenticated HTTP/1.1 client pipelined the start of a second request and then stopped reading, proxygen's…

CVE-2026-121737

Exploited
No known exploitation
Fix
Fixed in v2026.11.09.00
Who is exposed
Not reported

Do first: Upgrade to a fixed version: v2026.11.09.00.

Published
Last modified
Reference
Last checked
0/100 · provisional
None on Exploit-DB, Metasploit or GitHub

Summary

When a remote, unauthenticated HTTP/1.1 client pipelined the start of a second request and then stopped reading, proxygen's coroutine-based HTTP session could free that pipelined stream while resetting the connection's streams on the resulting write timeout, then go on to use it. This can crash the server, leading to denial of service, and may allow memory corruption with further impact. This issue affects proxygen versions prior to v2026.11.09.00.

cve.now Index

0Pcve.now Index 0 of 100 · methodology v3 · provisional
  • Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
  • Exposure?/25Unknown. No advisory context yet
  • Reach?/20Unknown. No tracked technology or package matched
  • Severity?/10Unknown. No CVSS score or vendor rating
  • No patch0/5No signal

What would change the score

  • Would score about 55 if added to CISA KEV
  • Would score about 50 if CISA's SSVC rates exploitation active
  • Would score about 22 if advisories confirm default setups are exposed

How the score works · Rankings

What to do

  • Upgrade to a fixed version: v2026.11.09.00.

Check your systems with an agent

Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.

Check whether my systems are affected by CVE-2026-121737 (When a remote, unauthenticated HTTP/1.1 client pipelined the start of a second request and then stopped reading, proxygen's…), using the cve.now data below.

Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.

What cve.now has for CVE-2026-121737 (entry last updated 2026-11-11):
Affected:
- Facebook proxygen: from v0.0.0.0, fixed in v2026.11.09.00
Fixed versions: v2026.11.09.00.
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
CISA KEV: CVE-2026-121737 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-121737 only. If you also check another CVE, look up its own KEV status; never assume it from this one.

How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.

Verify against the linked advisories before concluding, and cite the date you read each one:
- https://www.facebook.com/security/advisories/cve-2026-121737
- https://github.com/meta/proxygen/commit/daf245bba7fe1304b9491403fe56f91153299781
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.

Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.

Entry: https://cve.now/CVE-2026-121737
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-121737"}.

Timeline

  1. CVE published
  2. First seen by cve.now

Affected versions

  • Facebook proxygen

    From v0.0.0.0 · fixed in v2026.11.09.00

Evidence 4

Vendor advisory · 1

Establishes: Affected and fixed versions.

  1. Link

CVE record · 2

Establishes: The identifier and description.

  1. Record
  2. Record

Other links · 1

  1. Repository

Corrections

None so far.

Something wrong on this page? Report an error. Every fix is listed here.

Questions about CVE-2026-121737

Is CVE-2026-121737 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data

Which versions are affected by CVE-2026-121737?

proxygen: from v0.0.0.0 before v2026.11.09.00.Source: cve.now feed data

How do I fix CVE-2026-121737?

Upgrade to a fixed version: v2026.11.09.00.Source: cve.now feed data

Sources

More CVEs

Related