Heap-based buffer underflow in the modmul function in sshbn.c in PuTTY before 0.63 allows remote SSH servers to cause a denial of service (crash) and possibly trigger memory corruption or code execution via a crafted DSA signature, which is not properly handled when performing certain bit-shifting operations during modular multiplication
Published Aug 19, 2013
6.8
MEDIUMCVSS 2.0
EPSS 2.48%
Description
Heap-based buffer underflow in the modmul function in sshbn.c in PuTTY before 0.63 allows remote SSH servers to cause a denial of service (crash) and possibly trigger memory corruption or code execution via a crafted DSA signature, which is not properly handled when performing certain bit-shifting operations during modular multiplication.
Affected products
No data.
- 0.45
- 0.46
- 0.47
- 0.48
- 0.49
- 0.50
- 0.51
- 0.52
- 0.53b
- 0.54
- 0.55
- 0.56
- 0.57
- 0.58
- 0.59
- 0.60
- 0.61
- 2010-06-01
- ≤ 0.62
- 0.53
No data.
No Red Hat product state for this CVE.
No package ranges for this CVE.
Remediation
No remediation recorded yet.
Metrics
No CVSS v4.0 score for this CVE.
No CVSS v3.1 score for this CVE.
No CVSS v3.0 score for this CVE.
AV:N/AC:M/Au:N/C:P/I:P/A:P
This CVE is not in the KEV list.
No CISA SSVC assessment for this CVE yet.
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
Score over time
2022–2026- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Percentile over time
- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Table of values (9 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 2.48% (0.02475) | 83.97th | v5 (v2026.06.15) |
| Jun 15, 2026 | 2.48% (0.02484) | 82.47th | v5 (v2026.06.15) |
| Mar 17, 2025 | 1.14% (0.01136) | 76.91th | v4 (v2025.03.14) |
| Dec 12, 2024 | 1.27% (0.01268) | 86.25th | v3 (v2023.03.01) |
| May 16, 2024 | 1.48% (0.01481) | 86.73th | v3 (v2023.03.01) |
| Mar 7, 2023 | 1.48% (0.01481) | 84.73th | v3 (v2023.03.01) |
| Mar 6, 2023 | 3.07% (0.03073) | 83.74th | v2 (v2022.01.01) |
| Apr 1, 2022 | 3.07% (0.03073) | 82.08th | v2 (v2022.01.01) |
| Feb 4, 2022 | 3.07% (0.03073) | 64.71th | v2 (v2022.01.01) |
References (7)
- http://lists.opensuse.org/opensuse-updates/2013-08/msg00035.html vendor-advisoryx_refsource_SUSE
- http://secunia.com/advisories/54379 third-party-advisoryx_refsource_SECUNIAVendor Advisory
- http://secunia.com/advisories/54533 third-party-advisoryx_refsource_SECUNIA
- http://svn.tartarus.org/sgt/putty/sshbn.c?sortby=date&r1=9977&r2=9976&pathrev=9977 x_refsource_CONFIRMPatch
- http://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-modmul.html x_refsource_CONFIRMVendor Advisory
- http://www.debian.org/security/2013/dsa-2736 vendor-advisoryx_refsource_DEBIAN
- http://www.openwall.com/lists/oss-security/2013/08/06/11 mailing-listx_refsource_MLIST
| Link | Providers | Tags |
|---|---|---|
| http://lists.opensuse.org/opensuse-updates/2013-08/msg00035.html | vendor-advisoryx_refsource_SUSE | |
| http://secunia.com/advisories/54379 | third-party-advisoryx_refsource_SECUNIAVendor Advisory | |
| http://secunia.com/advisories/54533 | third-party-advisoryx_refsource_SECUNIA | |
| http://svn.tartarus.org/sgt/putty/sshbn.c?sortby=date&r1=9977&r2=9976&pathrev=9977 | x_refsource_CONFIRMPatch | |
| http://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-modmul.html | x_refsource_CONFIRMVendor Advisory | |
| http://www.debian.org/security/2013/dsa-2736 | vendor-advisoryx_refsource_DEBIAN | |
| http://www.openwall.com/lists/oss-security/2013/08/06/11 | mailing-listx_refsource_MLIST |
Change history (0)
No recorded changes yet.