Security readout for executives and security teams
Plain-English summary
This issue can let a remote party crash affected Asterisk systems during a specific T.38 fax negotiation path. The business impact is availability: calls or services handled by Asterisk may be interrupted. The source bundle does not provide CVSS scoring or evidence of active exploitation.
Executive priority
Treat this as a service availability risk for voice and fax infrastructure. Prioritize remediation where Asterisk handles production calling, fax workflows, or customer-facing communications, but do not classify it as confirmed exploited from the provided evidence.
Technical view
In res_pjsip_t38, affected Asterisk versions can crash when Asterisk initiates a T.38 re-invite and receives a response containing an m=image line with a zero port. The described root cause is an append operation against active topology where replace was expected.
Likely exposure
Exposure is likely limited to organizations running the affected Sangoma Asterisk or Certified Asterisk versions, especially where PJSIP and T.38 fax handling are in use. Debian-packaged Asterisk users should check the cited Debian advisories.
Exploitation context
The bundle states an attacker can trigger a crash through a crafted response to a T.38 re-invite initiated by Asterisk. It is not listed as KEV, and the provided sources do not claim active exploitation.
Researcher notes
This appears related in symptoms to CVE-2019-15297 but the bundle says the reason differs. Validate affected branches carefully, because the provided structured affected list is incomplete while the narrative description names specific fixed versions.
Mitigation direction
- Upgrade Asterisk 16.x to 16.16.2 or later.
- Upgrade Asterisk 17.x to 17.9.3 or later.
- Upgrade Asterisk 18.x to 18.2.2 or later.
- Upgrade Certified Asterisk to 16.8-cert7 or later.
- Apply Debian Asterisk security updates where Debian packages are used.
- Check Sangoma/Asterisk guidance before changing T.38 configuration.
Validation and detection
- Inventory Asterisk and Certified Asterisk versions across voice infrastructure.
- Confirm whether PJSIP and T.38 fax functionality are enabled or exposed.
- Verify installed packages meet the fixed versions named in advisories.
- Review service logs for unexplained crashes during fax or T.38 negotiation.
- Confirm Debian systems include the referenced DSA or DLA security updates.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2021-46837 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
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.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://downloads.asterisk.org/pub/security/AST-2021-006.htmlCVE reference
- [debian-lts-announce] 20221117 [SECURITY] [DLA 3194-1] asterisk security updateCVE reference · mailing-list
- DSA-5285CVE reference · vendor-advisory
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.