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Fencer Vulns
medium 5.9

CVE-2024-31497 json

In PuTTY 0.68 through 0.80 before 0.81, biased ECDSA nonce generation allows an attacker to recover a user's NIST P-521 secret key via a qu…

published 2024-04-15 2 y ago modified 2026-06-17 4 mo ago also EUVD-2024-29377

cvss
5.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
5.7%
EPSS 5.7% chance of exploitation in 30 days, percentile 93%
public exploits
0
none known

Summary

In PuTTY 0.68 through 0.80 before 0.81, biased ECDSA nonce generation allows an attacker to recover a user's NIST P-521 secret key via a quick attack in approximately 60 signatures. This is especially important in a scenario where an adversary is able to read messages signed by PuTTY or Pageant. The required set of signed messages may be publicly readable because they are stored in a public Git service that supports use of SSH for commit signing, and the signatures were made by Pageant through an agent-forwarding mechanism. In other words, an adversary may already have enough signature information to compromise a victim's private key, even if there is no further use of vulnerable PuTTY versions. After a key compromise, an adversary may be able to conduct supply-chain attacks on software maintained in Git. A second, independent scenario is that the adversary is an operator of an SSH server to which the victim authenticates (for remote login or file copy), even though this server is not fully trusted by the victim, and the victim uses the same private key for SSH connections to other services operated by other entities. Here, the rogue server operator (who would otherwise have no way to determine the victim's private key) can derive the victim's private key, and then use it for unauthorized access to those other services. If the other services include Git services, then again it may be possible to conduct supply-chain attacks on software maintained in Git. This also affects, for example, FileZilla before 3.67.0, WinSCP before 6.3.3, TortoiseGit before 2.15.0.1, and TortoiseSVN through 1.14.6.

Patch / fix

  • putty putty 0.81
  • putty Debian 12 0.78-2+deb12u2
  • putty Debian 14, Debian 13 0.81-1
  • filezilla Debian 14, Debian 13 3.67.0-1

debian advisories DEBIAN-CVE-2024-31497

  • putty openSUSE Tumbleweed 0.81-1.1
  • filezilla openSUSE Tumbleweed 3.67.0-1.1
  • putty Package Hub 15 SP5, openSUSE Leap 15.5 0.81-bp155.2.6.1

opensuse advisories openSUSE-SU-2024:13868-1openSUSE-SU-2024:13870-1openSUSE-SU-2024:0111-1

  • putty Alpine 3.24, Alpine 3.23, Alpine 3.22 +6 more 0.81-r0

alpine advisories ALPINE-CVE-2024-31497

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2024-31497 updated cvss 4.7

putty: secret key recovery of NIST P-521 private keys through biased ECDSA nonces in putty client

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

5.73% chance of exploitation in the next 30 days, higher than 93% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
CNA 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected products

  • putty putty

Classification

Weakness
  • CWE-338 Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.