CVE-2011-4939
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedThe pidgin_conv_chat_rename_user function in gtkconv.c in Pidgin before 2.10.2 allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) by changing a nickname while in an XMPP chat room.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceA NULL pointer dereference vulnerability exists in the pidgin_conv_chat_rename_user function in gtkconv.c of Pidgin instant messaging client before version 2.10.2. The vulnerability is triggered when a user changes their nickname while connected to an XMPP (Jabber) chat room, causing a denial of service through application crash.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data<= 2.10.1= 2.0.0= 2.0.1= 2.0.2= 2.1.0= 2.1.1= 2.2.0= 2.2.1= 2.2.2= 2.3.0= 2.3.1= 2.4.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Authentication
- None
- Confidentiality
- None
- Integrity
- Partial
- Availability
- Partial
AV:N/AC:L/Au:N/C:N/I:P/A:P
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check Pidgin versionRun 'pidgin --version' or 'purple-version' from terminal, or open Pidgin and go to Help > About to see the installed version numberAffected if The installed version is 2.10.1 or earlier, or matches any of these: 2.0.0, 2.0.1, 2.0.2, 2.1.0, 2.1.1, 2.2.0, 2.2.1, 2.2.2, 2.3.0, 2.3.1, 2.4.0
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Identify XMPP account usageOpen Pidgin, go to Accounts > Manage Accounts. Look for any account with protocol XMPP or JabberAffected if An active XMPP/Jabber account exists in the Pidgin configuration
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Check for active chat room sessionsIn Pidgin, look at the blist.xml or equivalent file in ~/.purple/ or examine currently open conversation windows for any group chat sessionsAffected if User is currently joined to any XMPP-based group chat room (MUC)
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Verify nickname change capabilityIn an active XMPP group chat, right-click on your own nickname and select Rename or use the chat room's nickname change feature if availableAffected if The vulnerability triggers specifically when changing your nickname while in an active XMPP chat room
You are affected if you use Pidgin version 2.10.1 or earlier with an active XMPP/Jabber account and change your nickname while in a group chat room, which will cause a crash due to NULL pointer dereference.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataUpgrade Pidgin to version 2.10.2 or later to patch the NULL pointer dereference in the nickname handling code for XMPP chat rooms.
- Consultation1.0 h
- Implementation1.0 h
- Testing1.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2011-4939 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2011-4939 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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