How severe is CVE-2013-0263?

No CVSS score has been assigned to CVE-2013-0263 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2013-0263?

CVE-2013-0263 affects the following packages: rack (RubyGems), rack (RubyGems), rack (RubyGems), rack (RubyGems), rack (RubyGems). Ecosystems affected: RubyGems.

How do I fix CVE-2013-0263?

Update rack to 1.5.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2013-0263 is resolved across your whole dependency graph.

How do I detect CVE-2013-0263 in my RubyGems dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rack, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2013-0263 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2013-0263 actively exploited in the wild?

No public exploit code has been indexed for CVE-2013-0263 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2013-0263?

CVE-2013-0263 has an EPSS (Exploit Prediction Scoring System) score of 5.4%, placing it in the 93th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

When was CVE-2013-0263 published, and has it been updated?

CVE-2013-0263 was published on February 8, 2013 and was last updated on March 23, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

💎 RubyGems

Not in CISA KEV

CVE-2013-0263 — rack

Fix: rack/rack@0cd7e9a

CVE-2013-0263 is a remote code execution vulnerability in rack. A fix is available for rack — see the affected versions and patch details below.

Rack arbitrary code execution via timing attack

Also known asGHSA-xc85-32mf-xpv8

Published

Feb 8, 2013

Updated

Mar 23, 2026

Affected

5 pkgs

Patched

5 / 5

Exploits

None indexed

Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

5.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs93th percentile — riskier than 93% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

5 pkgs affected

💎rack💎rack💎rack💎rack💎rack

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.

Description

Rack::Session::Cookie in Rack 1.5.x before 1.5.2, 1.4.x before 1.4.5, 1.3.x before 1.3.10, 1.2.x before 1.2.8, and 1.1.x before 1.1.6 allows remote attackers to guess the session cookie, gain privileges, and execute arbitrary code via a timing attack involving an HMAC comparison function that does not run in constant time.

Affected Packages

5 total 5 fixed

Ecosystem	Package	Vulnerable range	Fix
💎RubyGems	`rack`	≥ 1.5.0&&< 1.5.2	1.5.2`bundle update rack --conservative`
💎RubyGems	`rack`	≥ 1.4.0&&< 1.4.5	1.4.5`bundle update rack --conservative`
💎RubyGems	`rack`	≥ 1.3.0&&< 1.3.10	1.3.10`bundle update rack --conservative`
💎RubyGems	`rack`	≥ 1.2.0&&< 1.2.8	1.2.8`bundle update rack --conservative`
💎RubyGems	`rack`	≥ 1.1.0&&< 1.1.6	1.1.6`bundle update rack --conservative`

Affected Products

1 product · 28 configurations

Application

rackrack_project

28 versions

1.1.01.1.41.1.51.1.61.2.01.2.11.2.21.2.31.2.41.2.61.2.71.3.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rack, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update rack to 1.5.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2013-0263 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

Product	Fixed in	Advisory
Red Hat Subscription Asset Manager 1.2	`candlepin-0:0.7.24-1.el6_3`	RHSA-2013:0686
RHEL 6 Version of OpenShift Enterprise	`jenkins-0:1.502-1.el6op`	RHSA-2013:0638

Frequently Asked Questions

O3 Security · Impact-Aware SCA

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