CVE-2021-20048: A Stack-based buffer overflow in the SonicOS SessionID HTTP response header allows a remote authenticated attacker to cause Denial of Servic
Noroxi assessment
Priority: Monitor (action score 36/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 2% (FIRST EPSS); higher than 80.9% of all records.
- Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
- According to the record, no fixed version is available yet.
Low priority for now. Update when a fix is released; follow the vendor's advisory.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
A Stack-based buffer overflow in the SonicOS SessionID HTTP response header allows a remote authenticated attacker to cause Denial of Service (DoS) and potentially results in code execution in the firewall. This vulnerability affected SonicOS Gen 5, Gen 6 and Gen 7 firmware versions.
- Published
- Jan 10, 2022
- Updated
- Jun 16, 2026
- EPSS
- 2.0% · 80th percentile
- CWE
- CWE-121
Report tools
Action score
36
Monitor
Low priority for now.
- CVSS
- 35 / 40 · 8.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 1 / 30 · 2.0%
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- No fixed version yet
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| sonicwall | sonicos | cpe:2.3:o:sonicwall:sonicos |
| sonicwall | nsa 2650 | cpe:2.3:h:sonicwall:nsa_2650 |
| sonicwall | nsa 2700 | cpe:2.3:h:sonicwall:nsa_2700 |
| sonicwall | nsa 3650 | cpe:2.3:h:sonicwall:nsa_3650 |
| sonicwall | nsa 3700 | cpe:2.3:h:sonicwall:nsa_3700 |
| sonicwall | nsa 4650 | cpe:2.3:h:sonicwall:nsa_4650 |
| sonicwall | nsa 4700 | cpe:2.3:h:sonicwall:nsa_4700 |
| sonicwall | nsa 5650 | cpe:2.3:h:sonicwall:nsa_5650 |
| sonicwall | nsa 6650 | cpe:2.3:h:sonicwall:nsa_6650 |
| sonicwall | nsa 6700 | cpe:2.3:h:sonicwall:nsa_6700 |
| sonicwall | nsa 9250 | cpe:2.3:h:sonicwall:nsa_9250 |
| sonicwall | nsa 9450 | cpe:2.3:h:sonicwall:nsa_9450 |
and 47 more
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- sonicwall sonicosup to 7.0.1-r1456 inclusive
- sonicwall sonicosup to 7.0.1-5023-1349 inclusive
- sonicwall sonicosup to 7.0.1-5018-r1715 inclusive
- sonicwall sonicosup to 6.5.4.8 inclusive
- sonicwall sonicosup to 6.5.1.13-1n inclusive
- sonicwall sonicosup to 6.0.5.3-94o inclusive
- sonicwall sonicosup to 5.9.1.13 inclusive
Versions reported by the vendor
Affected version ranges reported by the assigning authority (sonicwall). Independent of NVD's CPE analysis and usually ahead of it.
SonicWall SonicOS
- 7.0.1-R146 and earlier, 7.0.1-5023-1349 and earlier, 7.0.1-5018-R1715 and earlier, 6.5.4.8-89n and earlier, 6.5.1.13-1n and earlier, 6.0.5.3-94o and earlier, 6.5.4.v_21s-1288 and earlier, 5.9.1.13 and earlieraffected
Same product
sonicwall: all recordsOther highest-scoring records for the same primary product.
- CVE-2024-53704An Improper Authentication vulnerability in the SSLVPN authentication mechanism allows a remote attacker to bypass authentication.KEV98Now
- CVE-2020-5135A buffer overflow vulnerability in SonicOS allows a remote attacker to cause Denial of Service (DoS) and potentially execute arbitrary code KEV77This week
- CVE-2024-40766An improper access control vulnerability has been identified in the SonicWall SonicOS management access, potentially leading to unauthorizedKEV75This week
Published before and after this one in the same product
- ← EarlierCVE-2021-20031Oct 12, 2021 · A Host Header Redirection vulnerability in SonicOS potentially allows a remote attacker to redirect firewall management users to arbitrary w28Monitor
- ← EarlierCVE-2021-20046Jan 10, 2022 · A Stack-based buffer overflow in the SonicOS HTTP Content-Length response header allows a remote authenticated attacker to cause Denial of S36Monitor
- Later →CVE-2022-22274Mar 25, 2022 · A Stack-based buffer overflow vulnerability in the SonicOS via HTTP request allows a remote unauthenticated attacker to cause Denial of Serv62This week
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
No fix version is recorded for this entry. Check the references for vendor advisories.
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
No history yet (it accumulates with the daily EPSS job).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- A low-privileged account is enough.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-121 · Stack-based Buffer OverflowCVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.
References
Vendor advisories and official records. Exploit/PoC links are deliberately left out.