Security readout for executives and security teams
Plain-English summary
CVE-2021-41079 can let an attacker knock vulnerable Apache Tomcat TLS services into an infinite loop, causing denial of service. The risk is mainly availability loss for affected Tomcat deployments using OpenSSL-backed NIO or NIO2 TLS connectors.
Executive priority
Treat this as an availability-risk update for exposed Tomcat services, especially customer-facing systems. Urgency depends on whether your deployment uses the specific OpenSSL-backed TLS connector configurations named in the advisory.
Technical view
Apache Tomcat 8.5.0-8.5.63, 9.0.0-M1-9.0.43, and 10.0.0-M1-10.0.2 did not properly validate incoming TLS packets when configured with NIO+OpenSSL or NIO2+OpenSSL. A crafted packet could trigger an infinite loop.
Likely exposure
Exposure is most likely on internet-facing or partner-facing Tomcat HTTPS services running affected versions with OpenSSL-backed NIO or NIO2 TLS enabled. Tomcat deployments using other TLS connector configurations may not match the described vulnerable condition.
Exploitation context
The source bundle states a specially crafted TLS packet can trigger denial of service. It does not provide evidence of active exploitation, and the CVE is not marked as CISA KEV in the provided data.
Researcher notes
The public record identifies CWE-20 input validation weakness and configuration-specific impact. The provided sources do not include CVSS, exploit telemetry, or detailed patch mechanics, so validation should focus on exact version and connector configuration.
Mitigation direction
- Upgrade affected Apache Tomcat versions using Apache or vendor guidance.
- Apply Debian tomcat8 security updates where Debian packages are used.
- Check NetApp guidance for affected NetApp-packaged or embedded Tomcat deployments.
- Prioritize exposed HTTPS services using NIO+OpenSSL or NIO2+OpenSSL.
- Use vendor advisories before changing connector behavior in production.
Validation and detection
- Inventory Tomcat versions across servers, containers, and appliances.
- Review TLS connector configuration for NIO+OpenSSL or NIO2+OpenSSL usage.
- Confirm installed versions are newer than the affected version ranges.
- Verify Debian or vendor package security updates are applied.
- Monitor affected services for abnormal CPU loops or availability degradation.
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.
CWE-20: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-41079 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://lists.apache.org/thread.html/rccdef0349fdf4fb73a4e4403095446d7fe6264e0a58e2df5c6799434%40%3Cannounce.tomcat.apache.org%3ECVE reference · x_refsource_MISC
- [debian-lts-announce] 20210922 [SECURITY] [DLA 2764-1] tomcat8 security updateCVE reference · mailing-list, x_refsource_MLIST
- https://security.netapp.com/advisory/ntap-20211008-0005/CVE reference · x_refsource_CONFIRM
- [tomcat-dev] 20211014 [SECURITY] CVE-2021-42340 Apache Tomcat DoSCVE reference · mailing-list, x_refsource_MLIST
- [tomcat-users] 20211014 [SECURITY] CVE-2021-42340 Apache Tomcat DoSCVE reference · mailing-list, x_refsource_MLIST
- DSA-4986CVE reference · vendor-advisory, x_refsource_DEBIAN
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.
Improper Input Validation
Improper Input Validation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.