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CVE-2013-4207· NVD / CVE Program· CNA redhat

Buffer overflow in sshbn.c in PuTTY before 0.63 allows remote SSH servers to cause a denial of service (crash) via an invalid DSA signature

Buffer overflow in sshbn.c in PuTTY before 0.63 allows remote SSH servers to cause a denial of service (crash) via an invalid DSA signature that is not properly handled during computation of a modular inverse and triggers the overflow during a division by zero by the bignum functionality, a different vulnerability than CVE-2013-4206.

MediumCVSS 4.3 · v2.0—No exploit Fix available
Published
Aug 19, 2013
Updated
Jun 16, 2026
EPSS
1.8% · 78th percentile
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Report tools

JSON

Action score

18

Monitor

Low priority for now.

CVSS
17 / 40 · 4.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 1.8%

Affected systems

VendorProduct
puttyputty
simon tathamputty

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • putty putty0.45
  • putty putty0.46
  • putty putty0.47
  • putty putty0.48
  • putty putty0.49
  • putty putty0.50
  • putty putty0.51
  • putty putty0.52
  • putty putty0.53b
  • putty putty0.54
  • putty putty0.55
  • putty putty0.56
  • putty putty0.57
  • putty putty0.58
  • putty putty0.59
  • putty putty0.60
  • putty putty0.61
  • putty putty2010-06-01
  • simon tatham puttyup to 0.62 inclusive
  • simon tatham putty0.53

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12filezillabefore 3.7.3-13.7.3-1
Debian:12puttybefore 0.63-10.63-1
Debian:6.0puttybefore 0.60+2010-02-20-1+squeeze20.60+2010-02-20-1+squeeze2
Debian:7puttybefore 0.62-9+deb7u10.62-9+deb7u1
openSUSE:Tumbleweedfilezillabefore 3.23.0.2-1.13.23.0.2-1.1

Same product

putty: all records

Other 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 a
    46Plan
  • 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_DE
    42Plan
  • CVE-2019-9898Potential recycling of random numbers used in cryptography exists within PuTTY before 0.71.
    40Plan
  • CVE-2019-9895In PuTTY versions before 0.71 on Unix, a remotely triggerable buffer overflow exists in any kind of server-to-client forwarding.
    40Plan
  • CVE-2019-17067PuTTY before 0.73 on Windows improperly opens port-forwarding listening sockets, which allows attackers to listen on the same port to steal
    39Monitor
  • CVE-2021-36367PuTTY through 0.75 proceeds with establishing an SSH session even if it has never sent a substantive authentication response.
    32Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:filezilla3.7.3-1 · Debian:12Package registry (OSV)
debian:putty0.63-1 · Debian:12Package registry (OSV)
opensuse:filezilla3.23.0.2-1.1 · openSUSE:TumbleweedPackage 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.

EPSS, last 120 days

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 researchers

Finders, 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

    If successful

    Confidentiality
    none
    Integrity
    none
    Availability
    P · the service can be disrupted
    Attack complexity
    M
    Confidentiality impact
    None
    Integrity impact
    None
    Availability impact
    P

    Weakness class (CWE)

    CWE-119 · Improper Restriction of Operations within the Bounds of a Memory Buffer

    CVSS vector

    AV:N/AC:M/Au:N/C:N/I:N/A:P

    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.

    ATT&CK techniques

    —

    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 help

    Change log

    1. Fix✗ → ✓

    For records you follow, these changes also arrive as notifications. →

    References

    Vendor advisories and official records. Exploit/PoC links are deliberately left out.

    All records