PuTTY bug ppk-longline-crash

Home | Licence | FAQ | Docs | Download | Keys | Links
Mirrors | Updates | Feedback | Changes | Wishlist | Team

summary: Long lines in PPK files (e.g. long key comments) can cause crash
class: bug: This is clearly an actual problem we want fixed.
difficulty: fun: Just needs tuits, and not many of them.
priority: high: This should be fixed in the next release.
present-in: 0.52 0.53 0.53b 0.54 0.55 0.56 0.57 2005-03-01
fixed-in: 2005-03-02 (0.58) (0.59) (0.60) (0.61) (0.62)

Long lines in PuTTY SSH-2 private key (.PPK) files could cause a one-byte buffer overflow, potentially leading to a crash. ("Long" here means header values or other lines of 128 characters or more.)

In practice, this is most likely to occur if a very long comment field is specified - I don't think there are any other circumstances under which PuTTYgen will generate keys with lines that long.

Although this fault has been present ever since SSH-2 public-key support was added to PuTTY, the report that led to its discovery indicated that it only failed in 0.57. This may be down to a change in the compiler version we used between 0.56 and 0.57.

Until the next release, if you want to continue to use release versions of the PuTTY tools, a workaround is to load any affected key into a snapshot version of PuTTYgen, trim the key comment, and then save the key back out - it should then work with 0.57 tools. (The key format hasn't changed since 0.57.)

Audit trail for this bug.


If you want to comment on this web site, see the Feedback page.
(last revision of this bug record was at 2005-03-02 00:13:52 +0000)