CVE-2011-1521

MEDIUMCVSS v2 · 6.46.4—
EchelonGraph scoreLOW confidence

This CVE was only ever scored under CVSS v2.0. NVD CVSS v2.0 base 6.4 — v2 rates that MEDIUM (v2 bands: LOW 0.0–3.9 / MEDIUM 4.0–6.9 / HIGH 7.0–10.0; v2 has no CRITICAL band). Vector AV:N/AC:L/Au:N/C:P/I:N/A:P. CVSS v2 is an older, coarser metric than v3.1/v4.0 (no Scope, no User Interaction, no Attack Requirements), so it is not directly comparable to a v3 or v4 score. NVD has never re-scored this record under v3. EPSS predicts 4.1% exploitation probability in the next 30 days, which is reflected in EG Risk but does not lift the v2 base. Confidence: LOW.

Sources: epss, nvd_v2
6.4EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 4%CVSS v2: 6.4Exploit: None knownExposed: 0

A fix is available — apply it.

The urllib and urllib2 modules in Python 2.x before 2.7.2 and 3.x before 3.2.1 process Location headers that specify redirection to file: URLs, which makes it easier for remote attackers to obtain sensitive information or cause a denial of service (resource consumption) via a crafted URL, as demonstrated by the file:///etc/passwd and file:///dev/zero URLs.

CVSS v2.0 (legacy)
6.4MEDIUMNVD never assigned a CVSS v3 rating to this CVE
EG Score
6.4(low)
EG Risk
35(Track)
EG Risk 35/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity64% × 45%
Exploitation4% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
4%
EPSS %ILE
90%
KEV
Not listed

Published

May 24, 2011

Last Modified

April 29, 2026

References (52)

Vendor Advisories for CVE-2011-1521(3)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(8)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntupython2.7 (2.7.2-5ubuntu1.1) @ oneiric2026-05-29ubuntu
ubuntupython2.4 (2.4.5-1ubuntu4.4) @ hardy2026-05-29ubuntu
ubuntupython2.6 (2.6.7-4ubuntu1.1) @ oneiric2026-05-29ubuntu
ubuntupython2.5 (2.5.2-2ubuntu6.2) @ hardy2026-05-29ubuntu
ubuntupython3.2-minimal (3.2-1ubuntu1.1) @ natty2026-05-29ubuntu
redhatpython-docs-0:2.6.6-2.el62011-05-19redhat
redhatpython-0:2.4.3-44.el52011-05-05redhat
redhatpython-0:2.3.4-14.10.el42011-05-05redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(2 across 2 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
python2.7—2.7.1-7—
Debian:6.0(1)
PackageVulnerable rangeFixed inDependents
python2.62.6.6-82.6.6-8+deb6u1—

Additional Vendor Advisories

(5)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 3× in last 7d / 13× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 125 total refreshes for this CVE.

  1. 2026-08-25 13:43 UTCEPSS rescore
  2. 2026-08-24 12:30 UTCOSV refresh
  3. 2026-08-19 16:58 UTCEPSS rescore
  4. 2026-08-18 13:42 UTCEPSS rescore
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  8. 2026-08-08 08:19 UTCOSV refresh
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  14. 2026-07-26 13:43 UTCEG score recompute▲ 6.40
  15. 2026-07-23 14:14 UTCEPSS rescore
  16. 2026-07-23 01:10 UTCOSV refresh
  17. 2026-07-23 01:04 UTCEG score recompute
  18. 2026-07-23 00:40 UTCEG score recompute
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  20. 2026-07-22 21:47 UTCEG score recompute
  21. 2026-07-22 14:03 UTCEPSS rescore
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  15. 2026-07-05 19:59 UTCOSV refresh
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  45. 2026-06-17 07:13 UTCOSV refresh
  46. 2026-06-16 17:49 UTCEPSS rescore
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  48. 2026-06-14 23:14 UTCEPSS rescore
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  50. 2026-06-13 22:57 UTCEPSS rescore
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  74. 2026-05-31 00:14 UTCEPSS rescore
  75. 2026-05-29 13:41 UTCEPSS rescore

Related CVEs(same vendor)

Frequently asked(4)

What is CVE-2011-1521?
CVE-2011-1521 is a medium vulnerability published on May 24, 2011. The urllib and urllib2 modules in Python 2.x before 2.7.2 and 3.x before 3.2.1 process Location headers that specify redirection to file: URLs, which makes it easier for remote attackers to obtain sensitive information or cause a denial of service (resource consumption) via a crafted URL, as…
When was CVE-2011-1521 disclosed?
CVE-2011-1521 was first published in the National Vulnerability Database on May 24, 2011, with the most recent update on April 29, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2011-1521 actively exploited?
CVE-2011-1521 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 4% probability of exploitation in the next 30 days, which ranks it in the top 10.0% of all scored CVEs.
How do I remediate CVE-2011-1521?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2011-1521, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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