CVE-2020-6831Public exploitNetwork attack vector

Memory corruption via oversized SCTP AUTH chunks

Published May 26, 2020 · Updated Aug 4, 2024

A WebRTC SCTP buffer overflow in Firefox before 76, Firefox ESR before 68.8, and Thunderbird before 68.8.0 allows remote attackers to corrupt memory. In usrsctplib/netinet/sctp_input.c, sctp_process_cookie_new passes an attacker-controlled AUTH chunk length to sctp_m_getptr without ensuring that it fits auth_chunk_buf. A peer can deliver the malformed chunk without authentication or user interaction, causing memory corruption and a crash; Mozilla did not confirm code execution.

CVSS severity9.8
Critical
EPSS probability5.80%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A WebRTC SCTP buffer overflow in Firefox before 76, Firefox ESR before 68.8, and Thunderbird before 68.8.0 allows remote attackers to corrupt memory. In usrsctplib/netinet/sctp_input.c, sctp_process_cookie_new passes an attacker-controlled AUTH chunk length to sctp_m_getptr without ensuring that it fits auth_chunk_buf. A peer can deliver the malformed chunk without authentication or user interaction, causing memory corruption and a crash; Mozilla did not confirm code execution.

The record

CVE
CVE-2020-6831
Published
May 26, 2020
Updated
Aug 4, 2024
Vendor
Mozilla
Product
Firefox
Classifications
CWE-787, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 26, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <76

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <76
Mozilla · Thunderbirdversion=unspecified <68.8.0
Mozilla · Firefox ESRversion=unspecified <68.8

Published CVSS scores

7.5NIST National Vulnerability DatabaseAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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