CVE-2020-14002: PuTTY 0.68 through 0.73 has an Observable Discrepancy leading to an information leak in the algorithm negotiation.
Noroxi assessment
Priority: Monitor (action score 24/100)
- 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: 3.1% (FIRST EPSS); higher than 87.9% of all records.
- Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. Special conditions such as timing or configuration are required.
- Fixed version: putty (Alpine:v3.10) 0.74-r0; putty (Debian:10) 0.74-1+deb11u1~deb10u1; putty (Debian:12) 0.74-1.
Low priority for now. Upgrade to putty (Alpine:v3.10) 0.74-r0; putty (Debian:10) 0.74-1+deb11u1~deb10u1; putty (Debian:12) 0.74-1 or later.
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
PuTTY 0.68 through 0.73 has an Observable Discrepancy leading to an information leak in the algorithm negotiation. This allows man-in-the-middle attackers to target initial connection attempts (where no host key for the server has been cached by the client).
- Published
- Jun 29, 2020
- Updated
- Jun 16, 2026
- EPSS
- 3.1% · 87th percentile
- CWE
- CWE-203
Report tools
Action score
24
Monitor
Low priority for now.
- CVSS
- 23 / 40 · 5.9 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 1 / 30 · 3.1%
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
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 |
|---|---|---|
| putty | putty | cpe:2.3:a:putty:putty |
| netapp | oncommand unified manager core package | cpe:2.3:a:netapp:oncommand_unified_manager_core_package |
| fedoraproject | fedora | cpe:2.3:o:fedoraproject:fedora |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- fedoraproject fedora31
- fedoraproject fedora32
- netapp oncommand unified manager core packageall versions
- putty putty0.68 and later · up to 0.73 inclusive
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Alpine:v3.10 | putty | from 0.68 · before 0.74-r0 | 0.74-r0 |
| Debian:10 | putty | before 0.74-1+deb11u1~deb10u1 | 0.74-1+deb11u1~deb10u1 |
| Debian:12 | putty | before 0.74-1 | 0.74-1 |
Same product
putty: all recordsOther highest-scoring records for the same primary product.
- CVE-2017-6542The ssh_agent_channel_data function in PuTTY before 0.68 allows remote attackers to have unspecified impact via a large length value in an a46Plan
- CVE-2004-1008Integer signedness error in the ssh2_rdpkt function in PuTTY before 0.56 allows remote attackers to execute arbitrary code via a SSH2_MSG_DE42Plan
- CVE-2019-9898Potential recycling of random numbers used in cryptography exists within PuTTY before 0.71.40Plan
Published before and after this one in the same product
- ← EarlierCVE-2019-17068Oct 1, 2019 · PuTTY before 0.73 mishandles the "bracketed paste mode" protection mechanism, which may allow a session to be affected by malicious clipboar31Monitor
- ← EarlierCVE-2019-17069Oct 1, 2019 · PuTTY before 0.73 might allow remote SSH-1 servers to cause a denial of service by accessing freed memory locations via an SSH1_MSG_DISCONNE31Monitor
- Later →CVE-2021-33500May 21, 2021 · PuTTY before 0.75 on Windows allows remote servers to cause a denial of service (Windows GUI hang) by telling the PuTTY window to change its31Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| alpine:putty | 0.74-r0 · Alpine:v3.10 | Package registry (OSV) |
| debian:putty | 0.74-1 · Debian:12 | Package registry (OSV) |
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.
- No account or password is required.
- No user action is required.
- Special conditions such as timing or configuration are required.
If successful
- Confidentiality
- high · data can be read
- Integrity
- none
- Availability
- none
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- None
- Availability impact
- None
Weakness class (CWE)
CWE-203 · Observable DiscrepancyCVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
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.
Attack patterns (CAPEC)
ATT&CK techniques
—
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (6 more)Show less
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/26TACCSQYYCPWAJYNAUIXJGZ5RGORJZV/
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JPV4A77EDCT4BTFO5BE26ZH72BG4E5IJ/
- lists.tartarus.org/pipermail/putty-announce/
- security.netapp.com/advisory/ntap-20200717-0003/
- www.chiark.greenend.org.uk/~sgtatham/putty/changes.html
- www.fzi.de/en/news/news/detail-en/artikel/fsa-2020-2-ausnutzung-eines-informationslecks-fuer-gezielte-mitm-angriffe-auf-ssh-clients/
Vendor advisories and official records. Exploit/PoC links are deliberately left out.