UltraVNC revision 1205 has stack-based buffer overflow vulnerability in VNC client code inside ShowConnInfo routine, which leads to a denial
UltraVNC revision 1205 has stack-based buffer overflow vulnerability in VNC client code inside ShowConnInfo routine, which leads to a denial of service (DoS) condition. This attack appear to be exploitable via network connectivity. User interaction is required to trigger this vulnerability. This vulnerability has been fixed in revision 1206.
- Published
- Mar 5, 2019
- Updated
- Jun 16, 2026
- EPSS
- 2.5% · 84th percentile
- CWE
- CWE-121
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Report tools
Action score
27
Monitor
Low priority for now.
- CVSS
- 26 / 40 · 6.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 1 / 30 · 2.5%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| uvnc | ultravnc | cpe:2.3:a:uvnc:ultravnc |
| siemens | sinumerik access mymachine\/p2p | cpe:2.3:a:siemens:sinumerik_access_mymachine\/p2p |
| siemens | sinumerik pcu base win10 software\/ipc | cpe:2.3:a:siemens:sinumerik_pcu_base_win10_software\/ipc |
| siemens | sinumerik pcu base win7 software\/ipc | cpe:2.3:a:siemens:sinumerik_pcu_base_win7_software\/ipc |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- siemens sinumerik access mymachine/p2pbefore 4.8
- siemens sinumerik pcu base win10 software/ipcbefore 14.00
- siemens sinumerik pcu base win7 software/ipcup to 12.01 inclusive
- uvnc ultravncbefore 1.2.2.3
Versions reported by the vendor
Affected version ranges reported by the assigning authority (Kaspersky). Independent of NVD's CPE analysis and usually ahead of it.
Kaspersky Lab UltraVNC
- 1.2.2.3affected
Same product
uvnc: all recordsOther highest-scoring records for the same primary product.
- CVE-2019-8274UltraVNC revision 1211 has a heap buffer overflow vulnerability in VNC server code inside file transfer offer handler, which can potentially41Plan
- CVE-2019-8273UltraVNC revision 1211 has a heap buffer overflow vulnerability in VNC server code inside file transfer request handler, which can potential41Plan
- CVE-2019-8271UltraVNC revision 1211 has a heap buffer overflow vulnerability in VNC server code inside file transfer handler, which can potentially resul41Plan
- CVE-2019-8280UltraVNC revision 1203 has out-of-bounds access vulnerability in VNC client inside RAW decoder, which can potentially result code execution.40Plan
- CVE-2019-8275UltraVNC revision 1211 has multiple improper null termination vulnerabilities in VNC server code, which result in out-of-bound data being ac40Plan
- CVE-2019-8272UltraVNC revision 1211 has multiple off-by-one vulnerabilities in VNC server code, which can potentially result in code execution.40Plan
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.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
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.
- No account or password is required.
- A user must open a link or visit a page.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
CWE-121 · Stack-based Buffer OverflowCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/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.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.
References
- cert-portal.siemens.com/productcert/pdf/ssa-286838.pdf
- cert-portal.siemens.com/productcert/pdf/ssa-927095.pdf
- cert-portal.siemens.com/productcert/pdf/ssa-940818.pdf
- ics-cert.kaspersky.com/advisories/klcert-advisories/2019/03/01/klcert-19-009-ultravnc-access-of-memory-location-after-end-of-buffer/
- ics-cert.kaspersky.com/advisories/klcert-advisories/2019/03/01/klcert-19-010-ultravnc-stack-based-buffer-overflow/
- us-cert.cisa.gov/ics/advisories/icsa-21-131-11
- www.us-cert.gov/ics/advisories/icsa-20-161-06
Vendor advisories and official records. Exploit/PoC links are deliberately left out.