CVE-2005-0687: Format string vulnerability in Hashcash 1.16 allows remote attackers to cause a denial of service (memory cons

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HIGH 7.5DOWNGRADE

CVE-2005-0687 is a high-severity flaw (CVSS 7.5) affecting hashcash. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Format string vulnerability in Hashcash 1.16 allows remote attackers to cause a denial of service (memory consumption) and possibly execute arbitrary code via format string specifiers in a reply address, which is not properly handled when printing the header.

Why this priority

High severity

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
EPSS exploit chance	2.9% (top 13%)
CISA exploited list	No
Published	2005-03-06
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: hashcash

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2005-03-06 05:00 UTCPublished CVE record published
2026-06-16 22:11 UTCUpdated Record last modified

hashcash hashcash DOWNGRADE

Affected: 1.14 · 1.15 · 1.16

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.14

1. Check installed version

apt-cache policy hashcash || rpm -q hashcash || hashcash --version

2. No fixed release: DOWNGRADE to a release before 1.14 (Debian / Ubuntu)

apt-cache madison hashcash sudo apt install hashcash=<VERSION_BEFORE_1.14> sudo apt-mark hold hashcash

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list hashcash sudo dnf downgrade hashcash-<VERSION_BEFORE_1.14> sudo dnf versionlock add hashcash

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2005-0687?

hashcash: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2005-0687 being exploited?

CVE-2005-0687 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2005-0687 affect?

CVE-2005-0687 affects hashcash. Severity is high (CVSS 7.5). Format string vulnerability in Hashcash 1.16 allows remote attackers to cause a denial of service (memory consumption) and possibly execute arbitrary code via format string specifiers in a reply address, which is not properly handled when p

How urgent is CVE-2005-0687?

Priority 48/100. High severity

Related CVEs

CVE-2012-4469 LOW 2.6 DOWNGRADE Cross-site scripting (XSS) vulnerability in the Hashcash module 6.x-2.x before 6.x-2.6 and 7.x-2.x before 7.x-
CVE-2006-3750 MEDIUM 6.8 DOWNGRADE PHP remote file inclusion vulnerability in server.php in the Hashcash Component (com_hashcash) 1.2.1 for Jooml
CVE-2006-3251 HIGH 7.5 UPGRADE Heap-based buffer overflow in the array_push function in hashcash.c for Hashcash before 1.21 might allow attac

References

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