CVE-2015-8803

CRITICALEPSS 90th pctl

9.8

CVSS v3

Description

The ecc_256_modp function in ecc-256.c in Nettle before 3.2 does not properly handle carry propagation and produces incorrect output in its implementation of the P-256 NIST elliptic curve, which allows attackers to have unspecified impact via unknown vectors, a different vulnerability than CVE-2015-8805.

CWE-254 CWE-310Cryptographic Issues

How to fix

Remediation Available

nettleDebian

Fixed in:3.2-1CVE-2015-8803

libnettle4Ubuntu

Fixed in:2.7.1-1ubuntu0.1USN-2897-1

nettleUbuntu

Fixed in:2.7.1-1ubuntu0.1USN-2897-1

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploit Intelligence

4.21%probability of exploitation in 30 days

90thpercentile

High risk: more likely to be exploited than 90% of all known CVEs.

References

Patch1

git.lysator.liu.se

Vendor Advisory1

lists.lysator.liu.se

Other references12

Related Vulnerabilities

Other CWE-254 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2016-0161	Medium	6.5	69%	-	-
CVE-2016-2296	Critical	9.4	64%	-	-
CVE-2015-1793	Medium	6.5	62%	-	Fix
CVE-2016-2118	High	7.5	37%	-	Fix
CVE-2016-3238	High	8.1	35%	-	-
CVE-2016-3198	Medium	6.5	32%	-	-

Common questions

How do I fix CVE-2015-8803?

Published advisories record a fix for 3 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.

Is CVE-2015-8803 being actively exploited?

Not that we know of. CVE-2015-8803 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 4.2% is the estimated probability that it will be exploited in the next 30 days. That is higher than 90% of all scored CVEs.

How severe is CVE-2015-8803?

CVE-2015-8803 has a CVSS v3 base score of 9.8, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2015-8803 affect?

Published advisories record a fix for nettle (Debian), libnettle4 (Ubuntu), nettle (Ubuntu). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-06.