CVE-2009-1955

HIGHNVD 7.58.1
EchelonGraph scoreHIGH confidence

“▲” beside the score: it is higher than NVD's CVSS score.

Score elevated to 8.1 because EPSS predicted 53% probability of exploitation within the next 30 days (98th percentile of EPSS-scored CVEs) when EchelonGraph scored this CVE. NVD baseline CVSS 7.5 retained for reference. Confidence: see factors.

Triggered by: EPSS exploit prediction (continuous uplift above 30%)
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Trending — 4 sources updated this weekWeaponized

Also known asEUVD-2009-1950 (ENISA EUVD) · GHSA-hfr6-pxvf-frf7 (GitHub Security Advisories)Source: ENISA EUVD

8.1EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • 648 internet-facing services (distinct ip:port) on record running an affected version — derived from Shodan data (© Shodan); a patched service can stay counted while its port stays open
  • High exploitation likelihood — EPSS 53%
  • Public exploit code is available (Exploit-DB, marked verified by Exploit-DB)
CISA-KEV: Not listedEPSS PROB: 53%CVSS: 7.5Exploit: Exploit-DB (verified)Exposed services: 648

A fix is available — apply it.

The expat XML parser in the apr_xml_* interface in xml/apr_xml.c in Apache APR-util before 1.3.7, as used in the mod_dav and mod_dav_svn modules in the Apache HTTP Server, allows remote attackers to cause a denial of service (memory consumption) via a crafted XML document containing a large number of nested entity references, as demonstrated by a PROPFIND request, a similar issue to CVE-2003-1564.

Internet exposure · derived from Shodan data

648 internet-facing services (distinct ip:port) on record running a version that maps to CVE-2009-1955, in our KEV-Exposure radar’s Shodan-derived sample.

across 67 countries (United States, Germany, Japan, France, Netherlands)top: http_server
See the KEV-Exposure radar →Derived from Shodan data. Shodan data is owned by Shodan, which holds its copyright (© Shodan). EchelonGraph claims no ownership of it or copyright in it. Aggregate, host-redacted.

How it counts: every 12 hours, when Shodan query credits allow, the radar runs one Shodan query per tracked product, reads up to 100 ip:port services per query, and keeps a service when its banner version matches a CISA-KEV or high-EPSS CVE; a service is dropped when neither a search nor a Shodan InternetDB port re-check has refreshed it for 21 days. A re-check that finds the port still listed by Shodan InternetDB refreshes the service without re-reading the banner, so a patched service can stay counted while its port stays open. A count is a banner-version inference over a sample, not an exploit test and not an internet-wide census, and the unit is a service, not a machine: a machine answering on two ports counts twice.

CVSS v3
7.5
EG Score
8.1HIGHhigh confidence
EG Risk
60
EG Risk 60/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity75% × 45%
Impact severity (EG Severity): CVSS 7.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation65% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 2 (Weaponized): a constant, not a probability.
Automatability0% × 15%
CISA's BOD 26-04 default: no one has published Automatable for this CVE, and CISA treats it as “no” for a CVE not in KEV.
SSVC (CISA's decision table, applied by EchelonGraph): Track at low, Track* at medium and Attend at high mission impact.
Exploitation public PoC (exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
53%
EPSS %ILE
98th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (8.1): severity, escalated by confirmed exploitation. This CVE's 8.1 is EPSS's lift toward 9.0 from its impact severity (EG Severity, CVSS 7.5 HIGH): a likelihood of exploitation, not impact.

EG Severity
7.5 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
53% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-28). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track* at medium mission impactTrack at low, Track* at medium and Attend at high mission impact.CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low, Track* at medium and Attend at high mission impact.

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

June 8, 2009

Last Modified

April 23, 2026

Advisory Details (8)

Auto-updated May 30, 2026
Patch available.
Web page

About Secunia Research | Flexera

http://secunia.com/advisories/35487
Web page

About Secunia Research | Flexera

http://secunia.com/advisories/35444
Web page

About Secunia Research | Flexera

http://secunia.com/advisories/35395
Web page

About Secunia Research | Flexera

http://secunia.com/advisories/35360
Web page

About Secunia Research | Flexera

http://secunia.com/advisories/35284
Web page

About Secunia Research | Flexera

http://secunia.com/advisories/34724
Web page

'[security bulletin] HPSBUX02612 SSRT100345 rev.1 - HP-UX Apache-based Web Server, Local Information' - MARC

http://marc.info/?l=bugtraq&m=129190899612998&w=2
Web page

'[PATCH] prevent "billion laughs" attack against expat' - MARC

http://marc.info/?l=apr-dev&m=124396021826125&w=2

Vendor Advisories for CVE-2009-1955(1)

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

Patch Availability(6)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntulibaprutil1 (1.2.12+dfsg-3ubuntu0.1) @ hardy2026-10-29ubuntu
ubuntuapache2-mpm-prefork (2.2.11-2ubuntu2.1) @ jaunty2026-10-29ubuntu
redhatxml-commons-0:1.3.02-2jpp_1rh2010-08-04redhat
redhathttpd22-0:2.2.10-23.1.ep5.el42009-07-17redhat
redhathttpd-0:2.0.46-73.ent2009-06-16redhat
redhatapr-util-0:1.2.7-7.el5_3.12009-06-16redhat

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

(6 across 6 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
apr-util—
  • every version up to 1.3.7+dfsg-1: fixed in 1.3.7+dfsg-1
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
apr-util—
  • every version up to 1.3.7+dfsg-1: fixed in 1.3.7+dfsg-1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
apr-util—
  • every version up to 1.3.7+dfsg-1: fixed in 1.3.7+dfsg-1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
apr-util—
  • every version up to 1.3.7+dfsg-1: fixed in 1.3.7+dfsg-1
—
Debian:4.0(1)
PackageVulnerable rangeFix by version rangeDependents
apr-util1.2.7+dfsg-2
  • every version up to 1.2.7+dfsg-2+etch2: fixed in 1.2.7+dfsg-2+etch2
—
Debian:5.0(1)
PackageVulnerable rangeFix by version rangeDependents
apr-util1.2.12+dfsg-8
  • every version up to 1.2.12+dfsg-8+lenny2: fixed in 1.2.12+dfsg-8+lenny2
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(5)

Data Freshness Timeline

(refreshed 8× in last 7d / 32× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 88 of 137 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 12 repeat rows among the latest 100 are merged into the row they repeat. The 49 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-31 16:26 UTCEPSS rescoreEPSS 53% · 98th percentile
  2. 2026-10-30 16:26 UTCEPSS rescoreEPSS 53% · 98th percentile
  3. 2026-10-29 16:26 UTCEPSS rescoreEPSS 53% · 98th percentile
  4. 2026-10-29 09:25 UTCEG score recompute
  5. 2026-10-29 09:25 UTCVendor advisory
  6. 2026-10-29 09:25 UTCGHSA enrichmentGHSA-hfr6-pxvf-frf7 · GitHub CVSS 7.5
  7. 2026-10-28 16:25 UTCEPSS rescoreEPSS 53% · 98th percentile
  8. 2026-10-27 16:25 UTCEPSS rescoreEPSS 53% · 98th percentile
  9. 2026-10-25 20:23 UTCEG score recompute
  10. 2026-10-25 16:25 UTCEPSS rescoreEPSS 53% · 98th percentile
  11. 2026-10-24 16:26 UTCEPSS rescoreEPSS 53% · 98th percentile
  12. 2026-10-23 16:25 UTCEPSS rescoreEPSS 53% · 98th percentile
  13. 2026-10-22 16:25 UTCEPSS rescoreEPSS 53% · 98th percentile
  14. 2026-10-22 11:05 UTCEG score recompute
  15. 2026-10-22 11:05 UTCVendor advisory
  16. 2026-10-22 11:04 UTCGHSA enrichmentGHSA-hfr6-pxvf-frf7 · GitHub CVSS 7.5
  17. 2026-10-21 16:25 UTCEPSS rescoreEPSS 53% · 98th percentile
  18. 2026-10-20 16:25 UTCEPSS rescoreEPSS 53% · 98th percentile
  19. 2026-10-19 16:25 UTCEPSS rescoreEPSS 53% · 98th percentile
  20. 2026-10-18 11:44 UTCEG score recompute
  21. 2026-10-17 16:26 UTCEPSS rescoreEPSS 53% · 98th percentile
  22. 2026-10-16 16:26 UTCEPSS rescoreEPSS 53% · 98th percentile
  23. 2026-10-15 16:25 UTCEPSS rescoreEPSS 53% · 98th percentile
  24. 2026-10-14 16:26 UTCEPSS rescoreEPSS 53% · 98th percentile
  25. 2026-10-13 16:26 UTCEPSS rescoreEPSS 53% · 98th percentile
Show 63 more
  1. 2026-10-12 21:46 UTCEG score recompute
  2. 2026-10-12 16:26 UTCEPSS rescoreEPSS 53% · 98th percentile
  3. 2026-10-12 01:53 UTCEG score recompute
  4. 2026-10-10 19:54 UTCEPSS rescoreEPSS 53% · 98th percentile
  5. 2026-10-09 20:00 UTCEPSS rescoreEPSS 53% · 98th percentile
  6. 2026-10-07 23:37 UTCEPSS rescoreEPSS 53% · 98th percentile
  7. 2026-10-06 15:09 UTCEPSS rescoreEPSS 53% · 98th percentile
  8. 2026-10-03 09:39 UTCOSV refresh
  9. 2026-09-30 14:58 UTCEPSS rescoreEPSS 53% · 98th percentile
  10. 2026-09-29 07:58 UTCEG score recompute
  11. 2026-09-27 13:39 UTCEPSS rescoreEPSS 53% · 98th percentile
  12. 2026-09-26 15:52 UTCEPSS rescoreEPSS 53% · 98th percentile
  13. 2026-09-24 13:57 UTCEPSS rescoreEPSS 53% · 98th percentile
  14. 2026-09-17 19:20 UTCEPSS rescoreEPSS 53% · 98th percentile
  15. 2026-09-15 03:04 UTCEPSS rescoreEPSS 53% · 98th percentile
  16. 2026-09-14 04:20 UTCOSV refresh
  17. 2026-09-12 14:54 UTCEPSS rescoreEPSS 53% · 98th percentile
  18. 2026-09-10 09:24 UTCEPSS rescoreEPSS 53% · 98th percentile
  19. 2026-09-06 13:41 UTCEPSS rescoreEPSS 53% · 98th percentile
  20. 2026-09-05 15:22 UTCEPSS rescoreEPSS 53% · 98th percentile
  21. 2026-09-04 13:55 UTCEPSS rescoreEPSS 53% · 98th percentile
  22. 2026-08-28 21:34 UTCEPSS rescoreEPSS 53% · 98th percentile
  23. 2026-08-26 05:41 UTCOSV refresh
  24. 2026-08-25 13:43 UTCEPSS rescoreEPSS 53% · 98th percentile
  25. 2026-08-19 16:58 UTCEPSS rescoreEPSS 53% · 98th percentile
  26. 2026-08-15 01:24 UTCEPSS rescoreEPSS 53% · 98th percentile
  27. 2026-08-09 22:10 UTCOSV refresh
  28. 2026-08-08 16:31 UTCEPSS rescoreEPSS 53% · 98th percentile
  29. 2026-08-06 13:41 UTCEPSS rescoreEPSS 53% · 98th percentile
  30. 2026-07-30 16:22 UTCEPSS rescoreEPSS 53% · 98th percentile
  31. 2026-07-30 01:26 UTCEPSS rescoreEPSS 53% · 98th percentile
  32. 2026-07-25 14:12 UTCEPSS rescoreEPSS 53% · 98th percentile
  33. 2026-07-24 22:41 UTCOSV refresh
  34. 2026-07-24 14:12 UTCEPSS rescoreEPSS 53% · 98th percentile
  35. 2026-07-23 14:14 UTCEPSS rescoreEPSS 53% · 98th percentile
  36. 2026-07-23 00:59 UTCEG score recompute
  37. 2026-07-23 00:37 UTCEG score recompute
  38. 2026-07-23 00:04 UTCEG score recompute▲ 0.60
  39. 2026-07-22 21:42 UTCEG score recompute
  40. 2026-07-22 14:03 UTCEPSS rescoreEPSS 53% · 98th percentile
  41. 2026-07-21 15:20 UTCEPSS rescoreEPSS 53% · 98th percentile
  42. 2026-07-20 17:03 UTCEPSS rescoreEPSS 53% · 98th percentile
  43. 2026-07-16 16:58 UTCEPSS rescoreEPSS 53% · 98th percentile
  44. 2026-07-15 16:54 UTCEPSS rescoreEPSS 53% · 98th percentile
  45. 2026-07-15 01:55 UTCEPSS rescoreEPSS 53% · 98th percentile
  46. 2026-07-13 06:07 UTCEPSS rescoreEPSS 53% · 98th percentile
  47. 2026-07-11 08:22 UTCEPSS rescoreEPSS 53% · 98th percentile
  48. 2026-07-09 19:04 UTCEPSS rescoreEPSS 53% · 98th percentile
  49. 2026-07-08 15:10 UTCEPSS rescoreEPSS 53% · 98th percentile
  50. 2026-07-07 18:11 UTCOSV refresh
  51. 2026-07-06 02:19 UTCEPSS rescoreEPSS 53% · 98th percentile
  52. 2026-07-01 15:02 UTCEPSS rescoreEPSS 53% · 98th percentile
  53. 2026-06-30 23:19 UTCEPSS rescoreEPSS 53% · 98th percentile
  54. 2026-06-28 04:52 UTCEPSS rescoreEPSS 53% · 98th percentile
  55. 2026-06-27 03:05 UTCEPSS rescoreEPSS 53% · 98th percentile
  56. 2026-06-25 13:46 UTCEPSS rescoreEPSS 53% · 98th percentile
  57. 2026-06-24 14:02 UTCEPSS rescoreEPSS 53% · 98th percentile
  58. 2026-06-23 21:29 UTCEPSS rescoreEPSS 53% · 98th percentile
  59. 2026-06-21 01:56 UTCEPSS rescoreEPSS 53% · 98th percentile
  60. 2026-06-19 05:25 UTCOSV refresh
  61. 2026-06-18 17:49 UTCEPSS rescoreEPSS 53% · 98th percentile
  62. 2026-06-17 17:49 UTCEPSS rescoreEPSS 53% · 98th percentile
  63. 2026-06-16 17:49 UTCEPSS rescoreEPSS 53% · 98th percentile

Publicly available exploits

(1 reference)

Public exploit code is referenced for this CVE (1 Exploit-DB entry). Defenders should treat patch urgency accordingly.

  • Exploit-DBEDB-8842✓ verified
    Published Jun 1, 2009

    Apache mod_dav / svn - Remote Denial of Service

    Open source ↗

Frequently asked(5)

What is CVE-2009-1955?
CVE-2009-1955 is a high-severity vulnerability; its CVE record was published on June 8, 2009. The expat XML parser in the apr_xml_* interface in xml/apr_xml.c in Apache APR-util before 1.3.7, as used in the mod_dav and mod_dav_svn modules in the Apache HTTP Server, allows remote attackers to cause a denial of service (memory consumption) via a crafted XML document containing a large number…
When was CVE-2009-1955 made public?
CVE-2009-1955 was made public on June 3, 2009: that is the date its CVE record's CNA, MITRE Corporation, gives for when the vulnerability was made public. The CVE record itself was published on June 8, 2009. EchelonGraph's copy of the record carries a last-modified date of April 23, 2026; the record at its source may have been updated since.
Is CVE-2009-1955 actively exploited?
CVE-2009-1955 is not currently on CISA's Known Exploited Vulnerabilities catalog. EchelonGraph's EG-KEV model places it in Tier 2 (Weaponized), which is not evidence of exploitation: Exploit-DB marks a public exploit for it as verified. EchelonGraph does not test whether exploit code works. FIRST EPSS estimates a 53% probability of exploitation in the next 30 days (98th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2009-1955?
CVE-2009-1955 has a CVSS v3 base score of 7.5 (NVD). EchelonGraph synthesises NVD + FIRST EPSS + GHSA into a combined EG score of 8.1 (HIGH).
How do I remediate CVE-2009-1955?
A fix for CVE-2009-1955 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2009-1955 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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